GRASS FAMILY 495 
Some other well-known, weeds of the family are the Cockle- 
burs, Ragweeds, Ironweeds, Spanish Needles, Wild Lettuce, 
and Beggar-ticks. , 
Monocotyledons 
Among Monocotyledons about 25,000 species are recognized, 
which are distributed among 42 families. They are less than 
one-fourth as numerous as the Dicotyledons. As previously 
stated, Monocotyledons differ from 
Dicotyledons in having flowers with 
parts usually in threes or sixes, leaves 
with parallel veins except in rare cases, 
and vascular bundles with the scattered 
arrangement. The Monocotyledons 
contain a few families of economic im- 
portance and one family that surpasses 
all other groups of Angiosperms in 
number of valuable food plants. 
Cat-tail Family (Typhaceae).— This 
family is mentioned because it includes 
the simplest of the Monocotyledons. 
They are aquatic plants, growing in 
groups in swamps and wet places. Some 
get as high as one’s head, and in the 
late summer and fall, when their in- 
florescences resembling a cat’s tail are Fic. 448.— The com- 
well formed, they are conspicuous plants mon Cat-tail (Thypha 
(Fig. 448). The flowers are monoecious — atifolia), showing the 
and have neither calyx nor corolla (Fig.  *etminal spikes of flowers 
ewe consisting of staminate 
449). The pistil is composed of one goyors above and pibtil- 
carpel containing one locule and only © fate flowers below (x4). 
one ovule. The staminate flowers are 
borne at the top and the pistillate flowers below on the spike. 
The pistil is supported by a stalk or stipe which develops hairs 
that become the brown down of the fruit. The stamens are at- 
tached directly to the axis of the spike and are intermixed with 
hairs. Asto whether the simple flowers of the Cat-tails are primi- 
tive or are reduced forms of more complex flowers is not known. 
Grass Family (Gramineae). — The Grasses constitute one of 
the largest families of Angiosperms and are widely distributed 
