92 3 ELEMENTARY BOTANY 
emerging from the anther cylinder, the style divides, exposing 
its stigmatic surfaces—the inner ones. In the case of insect — 
visits the stigmas are cross-pollinated, but if insect visits do 
not occur the stigmas bend outwards, curving until their tips 
touch the hairs on the outer surface of the style, and self 
pollination then takes place. | 
ae 1. Usually herbs ; trees and shrubs are com- 
teristics of paratively rare. This is remarkable when the 
the Order. enormous number of plants belonging to the 
Order is remembered. — 
2. Inflorescence, a capitulum. Lach so-called flower is an 
inflorescence. | | 
3. Stamens united by their anthers (syngenesious). 
4. Gynecium inferior, ovary one-celled, containing one 
basal ovule. 2 
5. Fruit is generally called a cypsela (Gk. kupsele=a hollow 
vessel), to distinguish it from those achenes which are formed 
from a single carpel and a superior ovary. 
6. Calyx forms a pappus and becomes an organ of disper-’ 
sion of the fruit. 
This is the most widely distributed of all 
Orders, and is also the most extensive; it 
includes as many as 800 genera, many of which are cultivated 
plants, as Sunflower, Jerusalem Artichoke, Dahlias, Zinnias, 
Marigolds. The number of genera indigenous to Britain is 
over forty. 
It is interesting to inquire why this Order should be so 
abundant. It has been suggested that the reason lies in the 
_ perfection of its arrangements for pollination, due (1) to the 
massing of the flowers in heads, and (2) to the structure of 
the flower, which is adapted for visits from all insects except 
the very short-lipped ones, and which at the same time pro- 
~ tects the honey and pollen. 
The provision of the Composite for the dispersion of their 
fruits must also be taken into consideration in accounting for 
the extensive distribution of the Order. ° 
Distribution. 
