NATURAL ORDERS 145 — 
7 
Se The plume-like stigmas protrude as soon as the 
Pollination. ; 
pales open, and as the pollen is borne by the wind, 
it is quite easy for them to catch the pollen. In some 
Grasses the stigmatic plumes are ready for pollination before 
the anthers are ripe, so that cross- pollination can take 
place. 
The pollen grain puts out its tube, which makes its way 
down between the cells of the stigma to the embryo sac of — 
the ovule ; fertilisation takes place, and the embryo begins to 
develop. The endosperm becomes laden with starch grains or 
sugar ; the ripe seed soon fills the ovary, and its wall becomes 
fused with that of the carpel, giving rise to the “ grain,” which 
is thus technically a fruit, not a seed. The embryo consists 
of radicle, plumule, and scutellum ; the rest of the grain is 
filled with endosperm. The germination of a Grass, such as 
Maize, is given in the ‘‘ Elementary Botany,” p. 5. 
Ecology of  Protessor Marshall Ward, in his “ Handbook 
the Order. on Grasses,’ thus classifies them according to 
habitat : : 
1. Meadow and Pasture Grasses. 
. Shade Grasses. 
. Aquatic and semi-aquatic Grasses. 
. Moor and Heather Grasses. 
. Seaside Grasses. 
. Ruderal or Vagabond Grasses. 
The first two classes are mesophytiec, the third hydrophytic, 
the fourth and fifth xerophytic, whilst the sixth class, as the 
term ‘“ vagabond” implies, is the most adaptable ; it includes, 
in fact, many species of the former classes, for a “ vagabond ” 
grass will flourish in a variety of conditions. 
If the leaves of these different classes are compared, it will 
be noticed that shade grasses have, as a rule, flat leaves, 
with a thin epidermis; in texture they are thin and her- 
baceous. Maritime grasses have narrow, upright, grooved 
or folded leaves, with a thick cuticle and water - storage 
tissue ; they are hard and leathery in structure. Leaves 
of moor grasses are, on the whole, hairy, though not so 
11—2 
So OU RH & bo 
