THE AMERICAN BOTANIST. 
85 
niaceae show the Hly-Hke character of six stamens. Unhke 
the orchids the seeds of this family often contain endosperm. 
It is the orchid family we usually think of when the 
Orchidales are mentioned; and well we may, for in point of 
variety form and color the flowers yield to no others. Some 
are noted for their bizarre forms and often resemble bees and 
other insects, others exhibit such beauty of color as to make 
them the most sought after of flowers, still others exhale de- 
lightful perfumes, but few are economically valuable to man 
with the single exception of the vanilla plant from whose 
pods the well-known flavor is obtained. 
The great majority of orchids are inhabitants of the tropi- 
cal forests where in common with other herbaceous plants 
they adopt an epiphytic life and thrive on the trunks and 
branches of trees. As the species extend toward the poles, they 
gradually descend to the earth. All the orchids of temperate 
regions are terrestrial, and practically all of them have the 
geophilous habit, that is, like the lily-worts, the life of the 
plant retreats to some underground rootstock, corm or tuber 
at the approach of cold weather. No less than three different 
kinds of roots have been distinguished in orchids. First there 
are the true earth roots,again there are roots for food storage 
and lastly there are aerial roots. Of these latter three varieties 
have been pointed out, namely roots for climbing, roots for 
absorbing nourishment from the decaying vegetation on the 
tree-trunks and the true aerial roots with a thick outer cortex 
designed to absorb rain, dew and the moisture of the air. All 
the orchids are herbs, seldom more than a few feet high, but 
in one tropical genus (Sobralia) they are erect and reach a 
height of nearly twenty feet. Many climbing forms occur, the 
vanilla being of this type. 
Most of the orchids store food in some way. The ter- 
restrial species usually store it in underground parts, but 
tropical species form curious green storage organs, called 
