~aAg FLOWERING PLANTS 
Butterfly and the Frog Orchids, is also spurred. The Butter- 
fly is very sweet-scented, and has el long spurs ; the 
Frog is green. 
The genus Ophrys differs from those just mentioned in 
having no spur. This includes the Bee, the Spider, and the 
Fly Orchids. 
The genus Neottia, the Bird’s-nest Orohid is so named from 
its rootstock, which consists of a dense mass of thick, rather 
succulent, fibres twisted in and out like a bird’s nest. It is 
pale brown in colour, and a Mie good gaat es of a sapro- 
phyte. 
The genus Cypripedium, or Lady’s Slipper, must be men- 
tioned, as it has 2 stamens. It consists of a single British 
species, found only in Durham and Yorkshire. | 
The genus Listera, Twayblade, is easily recognised by its 
two. broad ovate leaves, about 6 inches from the ground. The 
other species, with small cordate leaves, is a much more 
slender plant, belonging to mountain regions. 
Orchids abound in the tropics, where they are 
generally epiphytic. Their aerial roots either 
adhere to the bark of the supporting tree, securing the plant 
in its position, or they may hang loose in the air. 
Ecology. 
IRIDACEZ. 
YELLOW FLAG (Jris Pseudacorus). 
The Iris has an underground stem, which creeps 
along horizontally. The leaves are mostly radical ; the cauline 
leaves are arranged on opposite sides of the stem, and fit into 
each other, the outer bestriding the inner, somewhat in the 
same way as a rider sits astride the horse ; hence these leaves — 
are said to be equitant (Lat. equitare = to ride). 
The flowers are borne in the axils of the leaves, two or 
three together, in this species. They are epigynous, the 
perianth is petaloid, and the inner whorl of stamens is sup- 
pressed. 
Type. 
