PLANTS FROM THE BOLIVIAN ANDES. 81 
alike in habit, in which they resemble also the high-level plants 
of other portions of the world. The subaerial parts are dwarfed 
and seldom rise more than three inches above the surface of the 
ground. The leaves are usually thick with a distinct tendency to 
fleshiness. Extreme hairiness anda very coriaceous texture are 
alike uncommon. ‘The leaves are very commonly disposed in the 
form of a rosette ; many plants of the same species are frequently 
crowded together, giving rise to the turf-furmation * so frequently 
met with in cold and exposed situations. On the other hand, the 
subterranean organs attain an enormous development, which is 
seemingly out of all proportion to that of the aerial parts to 
which they belong. The root-system is usually either mono- 
podial, consisting of a deep stout taproot and its widely extended 
branches, or a fascicle of more or less fleshy roots. Since the 
upper layers of the soil are usually at a temperatare considerably 
below the minimum at which root-activity is possible, this fact is 
of great biological importance. In this connection it may be 
mentioned that the collection consists entirely of perennials ; 
annual plants are very rare, if indeed they exist at all, at high 
elevations. 
Omitting introduced species, the Conway collection contains 
thirty-eight species from 12,000 ft.f and above. These are 
distributed among thirty-one genera and twenty-one Natural 
Orders. 
Of the Natural Orders, the Loasacex (one species at 15,000 ft.) 
are an esseutially andine group, and are represented in the Old 
World only by the monotypic African and Arabiau genus 
Kissenia. Cactaces (one species at 14,270 ft.) is almost endemic» 
only one genus, 2hipsalis, being indigenous in the Old World. 
Valerianaces (one species at 18,000 ft.), though well represented 
in the Old World, attains a much greater and remarkable 
development in South America, particularly in the Andes: 
Weddell enumerates no less than twenty-nine alpine species of 
Valerianat. Fourteen species in the Conway Collection—rather 
more than one-third of the whole—belong to the Composite, the 
* Warming: Okol. Pfl.-Geogr. ; German trans., Berlin ( 1896), P- 99. 000 fi 
t+ Ball places the lower limit of the alpine zone on the Puna at 12, t. 
Journ. Linn. Soc., Bot. xxii. (1885) p. 6. 
} Chloris Andina, ii. pp. 17 et sqq. 
