86 
THE AMERICAN BOTANIST. 
pseudo-bulbs, which in reahty are thickened aerial stems. 
These may occasionally reach the size of a large cocoanut. 
Some of the terrestrial species, like their allies of the Bur- 
manniaceae are saprophytes, and still others are underground 
parasites, stealing part of their food, at least, from the roots 
of other plants. A few species have set up partnerships with 
fungi and some are so dependent upon their partners that their 
seeds seldom germinate without them. 
The leaves of orchids are parallel-veined and often linear, 
though many broad-leaved forms occur. In the epiphytic 
species which are often exposed to drying, the surfaces of 
the leaf are often very heavy and nearly impervious to water. 
Orchid flowxrs are too well known to need description. 
Suffice it to say that there are three greenish sepals, three col- 
ored petals, one of which usually differs in shape from the 
others and forms the so-called lip. There are never more 
than three stamens, seldom more than two and usually only 
one. The ovary is three-parted, but only two stigmas are us- 
ually functional. In many genera the stamens are united with 
the pistils to form what is called the column. The pollen 
often coheres in a sticky mass, which is transferred to other 
flowers by insect visitors, but some pollen is mealy and not 
a few orchids are able to set seed without the aid of insects. 
Judged from every point of view, the orchids are a highly 
specialized race of plants and clearly entitled to the place they 
hold as leaders of the Monocotyledons. The simplest flowers 
are without calyx and carolla and are wind-pollinated, in the 
orchids they have well developed calyx and corolla and are in- 
sect-pollinated ; in the simplest flowers all the parts are separate 
and often numerous, in the orchids the parts are united and all 
reduced to regular circles of three each, except the stamens 
which have less. The simple flowers are always regular and 
the orchids again show their superiority by extremely irregular 
flowers. In the orchids and other high types the flowers are 
