Introduction

This is a report of the Grupo Erskine expedition to central Patagonia in November and December 2006. The trip was conceived and planned by Peter Erskine but unfortunately, at the last minute, Peter had to withdraw for family reasons. His place was taken by David Haselgrove. The 2006 Grupo Erskine consisted of Hilary and Austin Little, Martin and Anna-Liisa Sheader, Hilary and John Birks, Chris Brickell, and David Haselgrove.

Grupo Erskine and the Alpine Garden Society have visited southern Patagonia several times, the last time in 2002, and have visited the Argentinean Lake District in northern Patagonia in 2004 and 2005. The obvious plan for 2006 was to try to fill the gap in the middle, namely the Andes and adjacent steppe near Lago Fontana and Lago General Vintter in central Patagonia. The major aim was to re-visit some of the localities that Carl Skottsberg visited in his amazing Patagonian expedition in 1907-1909 (Skottsberg, 1916). The plans were implemented by Oscar Pandolfi and Peter Erskine. The group flew, via Buenos Aires, to El Calafate in the south and then drove north over 3½ weeks to Carlos de Bariloche from where we flew back to Buenos Aires and London.

Grupo Erskine visited a wide range of climatic and ecological areas and habitats during the trip, and as a result we saw nearly 500 species of flowering plants and ferns (including fern allies). Not all these plants are strictly alpine plants. The list is not complete as I made no serious effort to identify all the grasses, sedges, or rushes in the steppe. The lists for the alpine sites are thought to be fairly complete as I attempted to identify all vascular plants present at these sites.

Patagonia – its environment

Patagonia is a remarkable area because of its vast size, its emptiness, its remoteness, its climatic extremes, its geological and topographical diversity, and its remarkable flora and fauna. In this section I summarise some of the main features of the Patagonian environment as a background for understanding the distributions and ecological behaviour of some of the plants we saw.

Patagonia, including Tierra del Fuego, is a huge territory more than 900,000 square kilometres located between 39° and 55° South. The topography is dominated in the west and south by the rugged Andean mountain chain, and in the east by dissected plateaux giving way to low, flat or gently undulating plains. This topography largely reflects the tectonic structure of the area, dominated by subduction of the Pacific oceanic crustal plate beneath the South American continent and active strike-slip faulting between plate fragments. Granitic intrusions and metamorphic rocks underlie much of the mountainous terrain, forming spectacular peaks in some areas. Late Mesozoic and early Tertiary sedimentary and volcanic rocks create a more tabular relief in the plateaux that decline eastwards. Throughout the 1.6+ million years of the Pleistocene, the western slopes of the Patagonian Andes have been periodically buried beneath massive ice-fields. In contrast to the spectacular glacial scenery superimposed on the structurally controlled topography in the west, the legacy from glaciation to the east is more subtle, where vast amounts of glacial and glaciofluvial deposits form rolling terrain composed of morainic ridges and mounds. These merge into immense plains of outwash gravel that extend to the Atlantic (McEwan et al. 1997).

The regional climate of Patagonia is strongly affected by the westerly storm tracks coupled with precipitation induced by the high western flanks of the Andean Cordillera. This produces a strong west-east gradient with annual precipitation of 4000-7000 mm falling on the western slopes of the Cordillera at 50°S, whereas less than 800 mm fall on the eastern side in Argentina due to a strong rain-shadow effect.

In addition to rainfall and temperature, wind is a major factor in the climate of Patagonia with the 'Roaring Forties' and the 'Furious Fifties'. As Coronato (1993) noted, "in few parts of the world is the climate of a region and its life so determined by a single meteorological element, as is the climate of Patagonia by the constancy and strength of the wind". Wind chill in Patagonia reduces the mean annual temperature perception by 4.2°C.

The vegetation patterns of Patagonia are closely related to the temperature and precipitation gradients. High winds and high rainfall (2000-5000 mm yr-1) extending along the west coast as far north as 48°S result in extensive areas of Magellanic moorland of bog communities and dwarf-shrub heaths. Where precipitation is between 800-4000 m yr-1 a temperate rainforest dominated by evergreen Nothofagus spp. (N. dombeyi in the north, N. betuloides in the south) occurs. In areas of lower precipitation the deciduous Nothofagus pumilio is often dominant. Deciduous forests of N. pumilio and N. antarctica occur along the eastern flanks of the Andean Cordillera up to an altitude of about 500 m where the precipitation is between 600 and 800 mm yr-1. Forest vegetation gives way eastwards as precipitation falls below 400 mm yr-1 to steppe grassland and shrub vegetation, dominated by tussock grasses and spiny shrubs. The dryness of the region is exacerbated by the combination of high evaporation and persistent strong westerly winds. Further details of the environment as well as an account of the prehistory and ethnography of Patagonia are given in McEwan et al. (1997), Bolzón and Bolzón (2005), and Correa (1969-1999).

Patagonia – its major vegetation regions

Argentinean botanists have divided the flora and vegetation of Argentina into 8 floristic dominions and 17 floristic provinces (Cabrera 1994, Bolzón and Bolzón 2005). Within Patagonia 4 dominions and 7 provinces or eco-regions occur (Bolzón and Bolzón 2005) (Figure 8). These provinces have a distinctive climate and support characteristic species and vegetation types (Cabrera 1994).

The 2006 expedition visited three provinces, namely Provincia Patagónica, Provincia Subantártica, and Provincia Altoandina (Figure 8). The major features of these provinces are as follows:

1. Provincia Patagónica. This eco-region is the largest in Patagonia, occupying about 534,460 km2 and it is sparsely populated. It stretches from the central Andean foothills in Mendoza to the south, gradually widening to cover the western part of the Neuquen and Rio Negro provinces and almost all of Chubut, Santa Cruz, and north-eastern Tierra del Fuego. It is bounded on the west by the Altoandina Provincia down to near parallel to 38°S and further to the Subantártica Provincia.

Soils are generally rocky and sandy, poor in fine material and organic matter. Climate is cold and dry, with some winter snow and frosts at any time. Mean annual temperatures range from 7.0 to 13.4°C, mean minimum temperatures 1.7 to 7.9°C, absolute minimum temperatures -5.4 to -24.5°C, and annual precipitation ranges from 116 to 422 mm (Esquel).

The dominant vegetation is steppe with a dominance of tussocky grasses and Mulinum spinosum. Some areas can be extremely species-rich, whereas others can be very species-poor. The reasons for these striking contrasts remain unclear but may be a function of soil, topography, land-use history, and current management.

2. Provincia Subantártica. This eco-region is shared between Argentina and Chile. In Argentina it stretches along a narrow strip up to 75 km wide but 2200 km long. The climate is temperate and wet in the north and cold and wet in the south. There is abundant snow in the winter and frosts can occur at almost any time. Precipitation increases from east to west and from north to south. Mean annual temperatures range from 5.4 to 9.5°C, mean minimum temperatures from 1.7 to 3.7°C, absolute minimum temperatures from -7.7 to -21.0°C, and annual precipitation from 814 to 1645 mm.

The soils are generally derived from volcanic ash and are thus rocky or sandy, well-drained, and low in organic content.

The dominant vegetation is deciduous or evergreen forest, dominated by Nothofagus spp., Araucaria araucana, or Fitzroya cupressoides. Nothofagus forests have a fascinating ecology and regeneration, with monospecific stands living to almost 500 years. Veblen et al. (1983, 1966) discuss the ecology of Patagonian forests in detail.

3. Provincia Altoandina. This includes the high peaks of the Andean range and some of the higher ridges in the foothills of the Patagonian Andes. Its distribution (Figure 8) is uneven as it occurs and overlaps on the highest mountains with Provincia Subantártica. Climate is cold and humidity increases with latitude. There are few modern climate data for this Province (Cabrera 1994). Annual mean temperatures range from -1.6 to 7.4°C (Mendoza), annual mean minimum temperatures vary from 0.6 to -5.4°C, absolute minimum temperatures are from -14.2 to -25.2°C, and annual precipitation varies greatly (as in any mountainous terrain) from 340 to 1590 mm (Cabrera 1994).

Vegetation is a mosaic of alpine grassland, snow-beds, wind-exposed ridges, and dwarf-shrub heaths. For details, see Ferreyra et al. (1998a) and Ward and Dimitri (1986). Good accounts of Altoandina flora and vegetation are given by Hoffman et al. (1998), Erskine (1994, 2001), Ferreyra et al. (1998b, 2006), and Chiapella and Ezcurra (1999). More specialised accounts for certain groups include Watson (1994).

I have recently been investigating what are the likely climatic ranges and requirements of the dominions and provinces or eco-regions delimited in Argentina (Canbrera 1994) and, in particular, the climatic ranges of the 4 dominions and 7 provinces in Patagonia. On the basis of Walter and Lieth’s (1970) Klima Diagram – Weltatlas, one can obtain a large amount of basic climatic data for annual mean temperature, annual precipitation (pcp), duration of the dry season (defined as months when precipitation in mm is less than twice the mean temperature in °C), and the number of months with monthly mean temperatures below 5°C.

The results are summarised as a key. Provinces visited by Grupo Erskine in 2002, 2004, and 2006 and the AGS in 2000 and 2005 are shown in bold.

Demarcation of the Altoandina climate is based mainly on guesswork because of the scarcity of climate stations. Presumably the period when the ground is frost-free is of particular significance ecologically. In the southern part of Provincia Altoandina (as far north as the Neuquen area), maximum precipitation occurs in winter and most of this falls as snow. Snow melt-water thus provides the principal source of water, so the most luxuriant vegetation tends to occur where the soil is able to retain the water, near snow-patches, and along melt-water streams. In the northern part of Provincia Altoandina, most of the precipitation falls as rain in the summer, so the ecological factors governing the local distribution of vegetation are likely to be different in this northern part of Provincia Altoandina.

Plant identifications

Thanks to the 7 parts and 8 volumes of Flora Patagonica (Correa 1969-1989), plant identification is relatively straightforward, assuming you can manage some botanical Spanish. Hilary Little has produced a very useful English translation of Spanish botanical terms. The illustrations for each species are generally very good and invaluable. Problems occurred in 2006 identifying certain cacti and orchids, and some Adesmia specimens.

Identification of cacti and orchids was helped with reference not only to Flora Patagonica but also to the small booklets by Kiesling and Ferrari (2005) and Freuler (2003), respectively. Calceolaria is a mildly frustrating genus but the work of Christine Ehrhart (2000) on Chilean Calceolaria helps to resolve some of the mess in Flora Patagonica's account. She, correctly I feel, brings together into Calceolaria polyrhiza the small and very variable C. lanceolata, C. polyrhiza, and C. prichardii. Her C. polyrhiza is thus a variable species with great variation in flower shape, spotting, and size. I am grateful to Austin Little for his skilful translation of the most important parts of Ehrhart (2000).

All the plant names on the species list are considered to be reliable and are unlikely to change in the near future. The one group that requires further, more detailed attention is Adesmia but it will be some months before any serious work can be started on these. If and when any progress is made, I will send the details to Grupo Erskine. The major problem with Adesmia determinations is that very little authoritatively named material that is essential for reliable verification of any identification exists in Norwegian or British herbaria.

Species List

This is the list of all the flowering plants and ferns that were seen and recorded. The individual lists for specific days are grouped into the main localities visited. The plants are grouped by families (in alphabetical order) within Pteridophyta, Gymnospermae, Angiospermae Dicotyledoneae, and Angiospermae Monocotyledoneae. I have added some short diagnostic notes for each species as a help to identifying photographs taken during the trip.

The list makes no attempt at being complete for introduced weeds and aliens or for grasses, sedges, or rushes in steppe or forest habitats. The lists for alpine areas are thought to be moderately complete, given the time of year we visited these areas.

Any introduced species is marked by an asterisk in the notes column and in the text. Taxonomy and nomenclature follow, as far as possible, Flora Patagonica (Correa 1969-1999) with some updates from Ehrhart (2000).

Localities Visited

Spelling of place names follows, wherever possible, Automovil Club Argentino 1:1,000,000 maps or the Zagier & Urruty 1:250,000 maps.

Estancia Huyliche – 24 November
We visited the upland area Estancia Huyliche near El Calafate. We approached it via a restaurant 800 m up on the side of the escarpment west of the town. We botanised from 820 m altitude to the summit areas at 1250 m, and descended to meet the vehicles at 680 m. 106 species were recorded (Table 1) within the treeless Southern Patagonian steppe and Southern Patagonian alpine vegetation with some areas of wind-blasted alpine desert. Many species of note were seen, including Oxalis enneaphylla, O. laciniata, Bolax caespitosa, Hamadryas delfinii, H. kingii, Xerodraba pycnophylloides, X. pectinata, Draba subglabrata, Olsynium biflorum in yellow, white-ish, and orange-brown forms, O. junceum, Anarthrophyllym desideratum, and the unusual Adesmia karraikensis. A few plants of the very rare Eudema monantha were found in very open ‘alpine desert’ areas at 1200 m.

Estancia Maria Elisa Franka – 25 November
In an exploratory mode, we visited Estancia Maria Elisa Franka about 35 km east of El Calafate. The vegetation was heavily grazed Southern Patagonian steppe and the areas we explored between 280 and 700 m were generally rather poor floristically. Only 85 species were recorded (Table 1). Plants of note included Junellia patagonica, J. azorelloides, Pterocactus australis, Corynabutilon bicolor, Calceolaria polyrhiza, Adesmia villosa, Astragalus patagonicus, and A. cruickshanksii. A large number of introduced species was recorded in and around the Estancia.

El Calafate – Estancia La Angostura – 26 November
This long drive was interrupted by several short scenic and botanical stops in the Southern Patagonian steppe. The stops were by the viewpoint of Lago Viedma (220 m), and at 430 m, 510 m, and 380-410 m altitude. A good range of steppe species were seen (Table 1), with the day’s total being 84 species. Particular attention was paid on this trip to Fabaceae, especially Adesmia. Our efforts were rewarded by finding eight Adesmia species on this day – A. aueri, A. ameghinoi, A. boronoides, A. campestris, A. dubia, A. guttulifera, A. lanata, A. lotoides – along with Astragalus cruickshanksii and A. ameghinoi, Anarthrophyllum desideratum, A. rigidum, and Vicia bijuga. Altogether, a legume-enthusiasts delight! Other plants of note included Junellia ulicina, J. o’donellii, J. azorelloides, J. patagonica, J. thymifolia, J. tonini, J. ulcina, J. ligustrina, and an unusual yellow Junellia plant (originally found by Lars Hansen and Kirsten Andersen), possibly a form of J. minutifolia, Fabiana nana, F. foliosa, Oxalis laciniata, Neobaclea crispifolia, Benthamiella patagonica, Xerodraba lycopodioides var. lycopodioides, the non-descript Philippiella patagonica, and many fine cushions of Oreopolis glacialis growing luxuriantly in the dry steppe. Several cacti were seen, including Pterocactus australis, Maihuenopsis darwinii, and Austrocactus patagonicus. The annual rainfall of the area we visited is probably about 250-300 mm, with January temperatures as low as -20?C, and an annual mean of about 12?C.

Estancia La Angostura – Estancia Menelik – 27 November
We continued driving through Southern Patagonian steppe all day, to reach Estancia Menelik (950 m) in the late afternoon. We had four stops in the steppe at 480 m, at 570 m, at 700 m by the deserted gas station at Los F. Houis, and at 900 m altitude. Only 58 species were recorded but what was lacking in quantity was more than compensated in the quality of some of the plants seen. Species of particular note seen included Petunia patagonica, Fabiana nana, Junellia ulicina, J. o’donelli, Adesmia suffocata, A. parviflora, A. villosa, A. lanata, A. lotoides, Benthamiella patagonica, B. azorella, B. ? azorelloides reported by Martin and Anna-Liisa Sheader, Xerodraba lycopodioides var. lycopodioides, Silene chilensis, Mulinum hallei, and, at the last stop as we approached Estancia Menelik, magnificent bushes of Anarthrophyllum desideratum in full flower, with Olsynium biflorum (yellow), Nardophyllum obtusifolium, Senecio vaginaefolius, and S. tricuspidatus.

Hills north-east of Estancia Menelik – 28 November
The bulk of Grupo Erskine explored the sandstone hills near Estancia Menelik between about 980 and 1320 m. The hills support a typical Patagonian Altoandina flora and 118 species were recorded, including Benthamiella patagonica (varying from pale to deep yellow), B. azorella, Calceolaria uniflora, C. polyrhiza and hybrids, Onuris papillosa, O. hatcheriana, Oxalis laciniata, O. loricata, O. enneaphylla, Primula magellanica, Silene antarctica, Hamadryas delfinii, Moschopsis rosulata, Tristagma nivale, Alopecurus magellanicus, etc. (see Table 1). Curiously no Viola auricolor was found, but this was seen in the N.P. Perito Moreno by Chris Brickell and David Haselgrove. The very flat lax Azorella fuegiana was found by Martin Sheader all around the Estancia.

Estancia Menelik – Hosteria La Serena by Lago Buenos Aires – 29 November
This long day of driving was broken by four stops in Southern Patagonian steppe. Only 51 species were noted. At the first stop by obsidian outcrops at 770 m, several interesting Adesmia species were found, including A. aphantha, A. patagonica, A. lotoides, A. suffocata, and A. tehuelcha, along with fine fragrant plants of Satureja darwinii. An unusual low-growing Adesmia with pale blue-white flowers was found in open areas. Of the taxa in Flora Patagonica, it is closest (but not an exact match) with A. ruiz-lealli. In the list it is given as A. cf. ruiz-lealli. Material was collected but I am still trying to find a professional taxonomist with an interest in Adesmia! The second stop at 660 m produced an additional tall and spiny Adesmia, A. rigida, along with fine plants of Junellia minutifolia. The third stop at 480 m had magnificent shows of Junellia thymifolia and Nassauvia glomerulosa, and three cacti, Austrocactus patagonicus, Pterocactus hickenii, and P. australis. The last stop, at the edge of an extinct volcanic rim at 980 m yielded Oxalis laciniata, Adesmia smithae, fine plants of Nastanthus patagonicus, and an umbel that was more troublesome to identify than usual, Azorella trifoliata. It is unlike any other Azorella species with stalks up to 10 cm high.

Mte Zeballos and Rio Zeballos – 30 November and 1 December
In these two days we explored several areas at different altitudes along Rio El Zeballos. A magnificent total of 151 species was recorded. The areas we explored on 30 Novemberwere shrub steppe at 750 m dominated by the bush Colliguaja integerrima above Los Antiguos, open areas and short turf between 1250 and 1370 m, and an area of Chloraea alpina at 1120 m. On 1 December we visited the top of the pass Po R. Roballos at 1490 m. We then climbed over very open and nearly barren ground to about 1520 m, and then ascended a col to the north towards Meseta Cuadraba at 1560 m and descended to meet the vehicles at 1320 m. Towards the end of the day, we visited an area of rock outcrops at 1150 m and a fine stand of Olsynium junceum at 1100 m near where we had lunched on the previous day. Magnificent rosettes of Viola auricolor were found in abundance and in full flower between 1150 and 1400 m. V. sacculus was found in small quantities above about 1450 m. Other plants of particular note included large low-growing mats of Discaria nana in full flower, Valeriana moyanoi, V. macrorhiza, Adesmia salicornoides, A. parviflora (blue), Hamadryas kingii, H. sempervoides, H. delfinii, Nassauvia lagascae (including var. globosa), Oxalis adenophylla, O. lacinata, Cynanchum nummulariifolium, and several small crucifers, including Draba gilliesii, D. magellanica, D. subglabrata, Onuris hatcheriana, O. papillosa, O. spegazziniana, Thlaspi magellanicum, and Cardamine cordata. It is unusual to find so many Onuris and Draba species growing in the same locality. Besides Azorella ameghinoi, A. fuegiana, A. lycopodioides, A. monanthos, A. trifoliata, and A. trifurcata, there was another distinctive tight mat-forming Azorella which we have called A. ‘caespitosa’, a taxon described by Skottsberg but now placed in Flora Patagonica in A. trifurcata and A. monanthos. The plants we have called A. ‘caespitosa’ are seemingly distinct and occurred as low mats in very exposed sites. Many other Patagonian Altoandina species were seen including Huanaca acaulis, H. andina, Mulinum hallei, M. valentinii, Pozoa coriacea, Caltha sagittata, Gnaphalium andicola, Hypochaeris incana, Lucilia alpina, Nassauvia pygmaea, Perezia recurvata, Nastanthus spathulatus, Gamocarpa selliana, Moschopsis rosulata, M. trilobata, Silene andicola, Pycnophyllopsis muscosa, Arenaria serpens, Plantago sempervivoides, P. barbata, Calandrinia caespitosa ‘skottsbergii’, Oreopolus glacialis, Benthamiella patagonica, Taraxacum gilliesii, Valeriana macrorhiza, Carex banksii, C. andina, C. acaulis, Tristagma nivale, Alopecurus magellanicus, Trisetum spicatum, and T. sclerophyllum. Martin and Anna-Liisa Sheader also found Benthamiella spezzagiana. Altogether this is a magnificent area with an amazing abundance of Viola auricolor and a fine range of Altoandina species. It was the fourth richest area we visited.

Lago General Carrera west of Chile Chico – 2 December
During travelling and the inevitable long procedure of leaving Argentina and entering Chile, we visited a range of shrub-steppe habitats, rocky slopes, and wet areas between 200 and 350 m altitude. Only 48 species were recorded. Some of the most interesting plants were in wet areas and boggy hollows within the rocky landscape. These included carpets of Arjona pusilla, growing with Pratia repens, Schoenus andinus, Aster valhii, Eleocharis albibracteata, and Oreobolus obtusangulus. Rock outcrops supported good stands of Cheilanthes glabra, Gaultheria mucronata, G. pumila, Calceolaria uniflora, C. biflora, C. polyrhiza, Escallonia rubra, Embothrium coccineum, Ribes cucullatum, Berberis buxifolia, B. heterophylla, and Saxifraga magellanica.

Rio Jeinemeni – 3 December
We tried to explore this valley but with limited success. We originally drove as far as possible until we reached the impassable river at 700 m. We then explored river gravels and an area of cliffs, screes, and grassland at 780 m. In the afternoon our guide, Guido Vittore, led us to the Valley of the Rocks (500-1075 m) where there are some ‘cave paintings’. Despite the unpromising look of the areas, the species total for the day was a very respectable 124. Many of the species seen were familiar Patagonian plants like Chloraea alpina, Anemone multifida, Benthamiella patagonica, etc. (see Table 1), but a few species of particular note were found. These included Senecio tristis, S. hollermeyeri, Gamocarpa selliana, Nastanthus chubutensis, N. spathulatus, Adesmia corymbosa, and the unusual A. burkartii. Viola auricolor was seen in small quantities at 930 m. A few bushes of the yellow Anarthrophyllum patagonicum were seen in open dry areas within steppe on the way up to the Valley of the Rocks. Plants colsely resembling Oxalis squamosa-radicata (sensu Flora Patagonica) were found in good flower along exposed ridges. The plants may be unusual forms of O. laciniata (also seen this day) or real O. squamosa-radicata.

Cerro Pico Sur – 4 December
We parked the vehicles at 750 m and then walked up through dry Southern Patagonian steppe and open Altoandina vegetation and even alpine desert to 1180 m. The area was very rich with 167 species being recorded. Many of the species seen on previous days were seen on this day, including many fine colonies of Viola auricolor, Oxalis adenophylla, O. loricata, O. laciniata, and Anarthrophyllum desideratum. It was a day for a legume-enthusiast with 9 species of Adesmia and 6 species of Astragalus. The unusual blue-white Adesmia cf. ruiz-lealli was found in some abundance in very open, wind-exposed areas. Other ‘alpine’ Adesmia species seen included A. salicornoides, A. parviflora (yellow and blue), and A. burkartii. In addition A. boronoides, A. corymbosa, A. guttulifera, A. lotoides, and A. suffocata were found at lower altitudes. Besides the familiar Astragalus cruickshanksii and A. nivicola, four additional Astragalus were found – A. domeykoanus with glabrous leaves and a flat mat in exposed areas, A. cf. pehuenches with broad leaves with hairy under-sides and a flat mat, again growing in open areas, A. patagonicus with very thin leaves and low short mats confined to very open, wind-exposed areas, and A. palenae, a medium-sized plant that is semi-erect. In addition, Lathyrus magellanicus, Vicia bijuga, Anarthrophyllum desideratum, and the introduced Trifolium repens boosted the Fabaceae score to 18 species. Other plants of particular note seen included Valeriana moyanoi, Plantage correae, Pycnophyllopsis muscosa looking just like a dense mat of the moss Polytrichum piliferum or P. juniperinum, eight species of Senecio, Silene chilensis, Erigeron patagonicus, the minute Minuartia acutiflora, Huanaca acaulis, and the local and curiously rare Scutellaria nummulariaefolia. Altogether this was an excellent day’s plant hunting within spectacular scenery of bizarre rock outcrops and open areas. It was the second richest locality we visited.

Steppe areas near Rio Mayo – 5 December
On the drive from Chile Chico to Rio Mayo, which involved crossing back into Argentina from Chile, we had three stops in the Southern Patagonian steppe at 750 m where there was a huge abundance of Adesmia boronoides, at 620 m where Junellia thymifolia was luxuriant, and at 590 m where Glandularia aurantiaca was abundant in a range of colour forms. Only 50 species were noted during these short stops. The most notable species seen included Junellia thymifolia, J. o’donellii, Glandularia aurantiaca, Adesmia pumila, A. aphantha, A. lotoides, A. campestris, A. guttulifera, A. rigida, Calandrinia patagonica, Mulinum leptacnthum, Senecio patagonicus, Oxalis laciniata, and Chuquiraga aurea.

Pampa del Chalta – Lago Blanco – 6 December
We drove from Rio Mayo to Estancia Siberia, with a short steppe stop at 650 m to admire excellent Junellia minutifolia. The area around Estancia Siberia (730-820 m) was heavily grazed Southern Patagonian steppe and sub-alpine steppe. Additional habitats visited included river gravels and saline pond margins. A total of 97 species was recorded. The most interesting area was the river gravels near the Estancia with Gamocarpa poeppigii, Mimulus glabratus, Cardamine glacialis, Epilobium australe, Arenaria serpens, and Nassauvia magellanica. Saline ponds and their margins supported Nitrophila australis, a minute, succulent-like plant looking like a mini-Salicornia, Samolus spathulatus, Juncus balticus, J. lesurii, J. depauperatus, and Myriophyllum quitense. Other plants of note recorded in the steppe included Adesmia villosa, A. pumila, A. rigida, A. aurantiaca, A. suffocata, A. parviflora, Mulinum hallei, Silene chilensis, Oxalis laciniata, Calceolaria polyrhiza, C. biflora, and Phacelia artemisioides.

Rio Mayo to Lago Fontana, Lago La Plata, and Pueblo Brondo – 7 December
This was primarily a travel day with short stops in the steppe (900 m) and in open areas (1060 m) within the forest of provincial Subantartica. Sixty-six species were recorded. Little not seen previously was found. Plants of particular interest included the orchids Codonorchis lessonii, Chloraea alpina and C. magellanica, Viola magellanica, V. reichii, Tristagma patagonicum, Fragaria chiloensis, the tree Nothofagus antarctica with Misodendron sp. or spp. growing parasitically on the Nothofagus, Satureja darwinii, Valeriana moyanoi (at 1060 m), and fine colonies of Sisyrinchium macrocarpum ssp. laetum in perfect flower.

Lago La Plata – Lago Fontana – 8 December
We explored Nothofagus antarctica and N. pumilio forest and a waterfall within the forest at 930-980 m. We also explored open (? cleared) areas and rock outcrops by the lake. It was very cold and windy. Nearby climate data indicate an annual precipitation of 900 mm and an absolute minimum of -22C.
The woodland and waterfall supported good colonies of Ourisia poeppigii growing by the stream. Additional species noted in the woodland included the large Tessaria absinthioides, Berberis serratodentata, B. buxifolia, Osmorhiza chilensis, Adenocaulon chilense, and Gunnera magellanica. Gaultheria mucronata was in fine fruit on dry rocks above the waterfall. Open areas supported large amounts of Chloraea alpina, some C. magellanica, and a curious array of hybrids. Rock outcrops and cliffs by the lake at 930 m had a good range of Altoandina ‘alpines’ including Perezia recurvata, Oreopolus glacialis, Silene chilensis, Draba magellanica, D. gilliesii, Saxifraga magellanica, Plantago barbata, Cheilanthes glauca, Cystopteris fragilis, and Leucheria leontopodioides. Calceolaria crenatiflora occurred locally in shaded cliff crevices. A total of 112 species was noted for the day.

North of Lago Fontana near Tres Montes (1861 m) – 9 December
After parking at 1070 m, we climbed through dense Mulinum spinosum steppe to avoid low-growing krummholz-like Nothofagus pumilio areas. We reached 1480 m along open, very wind-exposed ridges. A total of 133 species was recorded with an excellent range of Altoandina ‘alpines’. Plants of particular note included Viola sacculus (locally frequent), Combera paradoxa (not in flower), Stenodraba pusilla, Valeriana moyanoi, Cynanchum nummulariifolium, Loasa nana, Benthamiella patagonica (frequent on the summit areas and varying from very pale lemon to deep yellow in flower colour), Onuris graminifolia, O. papillosa, O. hatcheriana, Draba gilliesii, D. magellanica, Silene antarctica, S. andina, S. chilensis, Plantago sempervivoides, Oxalis loricata, O. adenophylla, Nassauvia lagascae, N. pygmaea, N. abbreviata, and N. juniperina. The genus Adesmia was well represented with A. boronoides, A. corymbosa, A. parviflora, A. retusa, and the mysterious A. cf. ruiz-lealli, as was Astragalus with A. cruickshanksii, A. nivicola, and A. palenae. The small Polemonium micrantha was found in short turf on the descent. Overall this was a very good and rewarding locality and it was the third richest locality we visited.

Lago Fontana to Rio Pico – 10 December
This was primarily a travelling day but we had two stops in the Patagonian steppe, one at 610 m and the second at 870 m. The first stop by a gas-station was productive botanically with the horned poppy Glaucium flavum, growing as a roadside plant. The local steppe had Junellia ulicina, Acantholippia seriphioides, Glandularia macrospermum, and Tetraglochin caespitosum. In a derelict football pitch nearby, Lecanophora ruiz-leallii was found in small quantity. The second stop was for a Junellia that was growing in abundance. Its specific identity is still not clear. Only 37 taxa were noted for the day.

Lago General Vintter near Rio Pico – 11-13 December
In these three days we explored the area around Lago General Vintter, attempted to visit Lago Azul, and, with Guido Vittone’s expert navigation climbed through Nothofagus forest to explore an alpine ridge north of Lago Guacho north of Lago Vintter. As many of the same species were noted on the different days, the list (Table1) gives all the species seen on these three days.

On December 11 we primarily visited dry alpine-steppe areas on glacier outwash sands and moraines and ‘balds’ within Nothofagus pumilio forest at 1000-1180 m. We also visited some small lakes and associated wet areas towards Lago del Engamo. The most interesting plants seen in open areas were Viola columnaris (not in flower), V. sacculus, Barneoudia major, an Adesmia that cannot be satisfactorily identified but id listed in Table 1 as Adesmia sp.2, the same plant that was found on the AGS N Patagonia 2005 expedition further north, Nardophyllum chiliotrichoides, Tristagma nivale, Calandrinia hirtella, and Stenodraba chillanensis. The usual range of Altoandina plants were also seen, including Oreopolus glacialis, Draba gilliesii, D. magellanica, Saxifraga magellanica, Arenaria serpens, etc. (see Table 1). Magnificent stands of Oxalis adenophylla were found on the shore of Lago Vintter at 970 m elevation. Lunch by small ponds nearby produced several plants of note including the rare Botrychium dusenii, Anagallis alternifolia, Gentiana prostata, Potamogeton linguatus, Carex darwinii, C. subantarctica, and C. nebularum.

On December 12 we tried to reach Lago Azul but with no success. We drove instead to Lago No. 4 and examined forest edges, river gravels, wet areas, and roadsides. Plants of note seen included Ovidia andina, Embothrium coccineum, Calceolaria borsinii, Chloraea cf. philippi, Mutisia oligodon, M. spinosa, Lomatia hirsuta, Adesmia silvestrii (on river gravels), Carex acutata, Geum magellanicum, and Blechnum microphyllum.

On December 13 we followed Guido Vittore through featureless Nothofagus pumilio forest for several hours, noting typical forest plants like Rubus geoides, Berberis serratodentata, Macrachaenium gracile var. radiatum, Adenocaulon chilense, Polystichum andinum, Lycopodium paniculatum, Gavilea sp., and an unknown low shrub (? Celastraceae) to emerge at the tree-line at 1450 m. It was a most impressive piece of field-craft done without a compass, map, or GPS! The alpine areas were difficult to search because of extreme cold and fierce winds. Plants of particular note recorded by the hardier members of Grupo Erskine included Viola sacculus, Hamadryas kingii, Valeriana macrorhiza, Chilotrichum diffusum, Adesmia parviflora, Lucilia alpina, Stenodraba pusilla, Azorella ‘caespitosa’, Antennaria chilensis, Gnaphalium andicola, Cardamine glacialis, Epilobium glaucum, Pycnophyllopsis muscosa, Carex andina, and C. patagonica.

Our explorations of the Lago General Vintter area as a whole produced an impressive 188 species, the richest area we visited.

Rio Pico – Esquel – 14 December
This was, yet again, a travelling day. We had a rewarding stop at a large sandstone rock outcrop at 850 m within open Austrocedrus chilensis woodland. Besides fine bushes of Fabiana imbricata and Escallonia rubra, ferns were well represented in cliff crevices, with Cheilanthes glabra and Polystichum andinum. The roadside areas and forest margins were excellent for orchids with Codonorchis lessonii, Chloraea alpina, C. magellanica, C. alpina x magellanica, C. cylindrostachya, and Gavilea odoratissima. Ninety species were noted for the day.

La Hoya near Esquel – 15 December
After driving to an unexplored mountain near Esquel, finding magnificent white and pink Mutisia spinosa, and deciding there was no easy access, we visited the well-known La Hoya. We parked at 1200 m. There was much less snow than on previous visits in late November so Hilary Birks and I struck up to the cliffs and screes below the summit ridge at 2050 m. Besides finding a small lake at 1970 m, the botany was disappointing with several of the species previously seen up to 1860 m simply extending higher but growing in ever decreasing amounts. Plants of note seen above 1860 m included Oxalis erythrorhiza (many fine cushions), Nassauvia pygmaea, N. ameghonoi, N. revoluta, N. dusenii, N. juniperina, N. argyrophylla, N. lagascae, Viola sacculus, Onuris graminifolia, and Silene antarctica. At lower altitudes, the group saw all the ‘usual’ La Hoya species, including Ranunculus semiverticallatus (going over but still with some good flowers), Tristagma sessile, Hamadryas kingii, Caltha sagittata, C. appendiculata, and Ourisia poeppigii. I took advantage of the reduced snow-cover at 1200-1400 m to explore the flora of hollows normally covered by snow along the cascading stream. Eight species of Carex, including the European C. capitata and C. magellanica, were found, along with Schoenus andinus, Eleocharis pachycarpa, and Oreobolus obtusangulus. A total of 103 species was recorded, compared with 61 seen with the AGS in 2005 and 60 with Grupo Erskine in 2004.

Carlos de Bariloche area – 17 December
The day was very wet and windy. Hilary Birks and I tried to leave to fly to Buenos Aires and eventually flew into the worst storm ever experienced in historical times in Buenos Aires. Meanwhile, Grupo Erskine visited Mirador del Nirihuana and some steppe near Bariloche and recorded 76 species in spite of the terrible conditions. Plants of particular note included Loasa bergii, Moschopsis caleofuensis, Nastanthus patagonicus, N. spathulatus, Tristagma nivale, Valeriana moyanoi, Viola columnaris, and Barneoudia major. In the woodland Calceolaria crenatiflora, Ourisia poepiggii, Perezia prenanthoides, Gavilea lutea, Codonorchis lessonii, and Polystichum andinum were of interest. In the steppe east of Bariloche, Rhodophiala mendocina, Cassia arnottiana, Mutisia spinosa, Junellia succulentifolia, and J. o’donelii were of interest.

Final Comments

During the trip with its travel of 2300 km across 9° longitude, we saw a total of 493 species, about 25% of the total Patagonian flora. We botanised in temperate grassland (= Patagonian steppe and scrub), temperate woodland (Austrocedrus), temperate forest (Nothofagus), and alpine vegetation. The richest areas are in the Provincia Patagónica and Provincia Altoandina.

Of the 493 species seen in 2006, 268 of these species were also seen on the AGS Northern Patagonia tour 2005 and the Grupo Erskine tour to northern Patagonia in 2004. 225 species were seen in 2006 but not seen in 2005 or 2004, whereas 229 species were seen in 2004 or 2005 but not in 2006. Allowing for the inevitable vagaries in field recording of plants, for my increasing familiarity with the Patagonian flora, especially grasses, sedges, and rushes, and for different habitats visited in 2005 and 2006, the general picture is that there is a ‘core’ of about 270 species seemingly common to both central and northern Patagonia, about 230 species seemingly confined to northern Patagonia, and about 225 species seemingly confined to central Patagonia.

The most striking botanical changes along the strong east-west gradient (increasing precipitation) are changes in vegetation structure, biomass, and production, leading to high forests of Nothofagus where there are 600 mm or more annual rainfall. Highest species richness (numbers of species in 1 m2) probably occurs in some steppe areas.
Work is currently in progress in compiling all records of Altoandina plants seen in different localities by the AGS in 2000 and 2005 and by Grupo Erskine in 2002, 2004, and 2006 to detect what species occur throughout the mountain chain, which are confined to particular areas, and which show no patterns in their distribution from south to north. The results of this analysis will be circulated to Grupo Erskine in due course.

A more subtle gradient is the progressive decrease in the number of alpine plants as one moves south-wards. For the mountains we visited, there is an average decrease of about 6 species per 1° latitude increase. There are many possible reasons for such a pattern, including climate, particularly the length of the growing season, habitat area, and evolutionary and ecological history.

There is also an altitudinal gradient in alpine species richness in our data, with a nearly constant decrease in alpine richness of 10 species per 100 m altitude. Again there are many possible reasons. The most compelling one is based on the facts that (1) species richness is proportional to area (a basic ecological law) and that (2) the area per 100 m up mountains naturally decreases with altitude. There is thus less area with increasing altitude and hence one would expect a priori fewer species with increasing elevation. Even when this area-effect is allowed for, the unexplained variation in alpine species richness may be a result of mountain isolation and hence dispersal, availability of habitats, bedrock geology, area of snow-free ground, historical factors, and chance.

The Patagonian flora is a fascinating and challenging mixture of steppe, forest, and alpine plants. The Grupo Erskine 2006 tour was able to see a wide cross-section of this flora. Hopefully by exploring some of the patterns hidden in our species lists, we can contribute to our understanding of alpine plant richness in Patagonia, especially of the Altoandina flora.

Acknowledgements

Grupo Erskine is greatly indebted to Peter Erskine for devising and planning this trip and for so generously sharing his research on Patagonia and its botany. We are all very sorry that Peter was unable to come. The Grupo is also very grateful to Hilary Little for managing the tour, to Guido Vittore for his expert guiding and for sharing his great knowledge of Patagonia and its diverse landscapes with us, and to Daniel Denuncio for his skilful driving. I am greatly indebted to Cathy Jenks for her invaluable help and skill in deciphering my species lists and in preparing this report. I appreciate the botanical help of Grupo Erskine whilst we were together in Patagonia, in particular Martin and Anna-Liisa Sheader, Hilary Birks, Chris Brickell, and Hilary Little who excelled at finding so many different (and difficult!) small Adesmia species.

References