36o NOTES OF A BOTANIST 
the least possible surface to the onslaught of the 
flood. 
When we reach the upper margin of vegetation, 
where the inclination of the rock is at least 45^ 
we find that the plant which by its resistance to the 
full force of the flood helps to sustain all those 
below it is a Bromeliacea with leaves somewhat 
like those of the pineapple but less rigid, and its 
dead flower- stems 6 feet high. Below this are 
beds of an Orchis (^Sobralia dickotoma), whose tufted, 
distichous, leafy stems rise 5 or 6 feet high and 
bear at the summit a few large, handsome, aromatic 
flowers, of which all the parts are white save the 
lip, which is yellow within with vermilion streaks. 
About the roots of this orchis were the tufts of a 
moss (a Calymperes) in fruit, apparently the same 
species as is frequent in the low sandy forest 
throughout the Alto Rio Negro. The only other 
herbaceous plants seen here were a Cyperacea 
(Scleria sp.), a Scrophulacea with red flowers 
about the size of those of A^ttirrhinum majus, a 
minute Utricularia with greenish white flowers in 
places where water constantly trickled down, and 
a slender Dioscorea. Twining along with the last 
over the Orchis and the Bromeliacea was a suffruti- 
cose Echites, remarkable for its large white bracts 
with roseate tips. The arboreous vegetation com- 
prises an Ivy, a Cordia (C graveolens) with aromatic 
leaves, a Melastoma with large white flowers, and a 
Malpighaceous shrub with erect compound racemes 
of yellow flowers ; the same species grows in 
large patches at the mouth of Guainia, and at a 
short distance bears a great resemblance to the 
common broom ; and some others which, not being 
