16 FAMILIES OF FLOWERING PLANTS. 
they appeared on the earth’s surface in advance of the Dicotyledons. 
The three Monocotyledonous orders which will be discussed in this 
paper consist entirely of aquatic or marsh plants, most of them with 
From ‘‘oulter’s ‘‘ Plant Relations.” 
Copyrigh*, 1599, by D. Appleton & Co. 
Fic. 11.—Section of box-elder twig show- 
ing the annual rings of growth, the vascular 
region (w) the pith rays (m) and the cortex 
(c). : 
inconspicuous flowers and little or no 
economic value. (See Fig. 12.) The 
Pandanales are herbs, shrubs or 
trees, their flowers with a perianth 
composed merely of bristles or chaffy 
scales. The Helobiae (so named in 
allusion to their marsh loving pro- 
pensities) are all herbs, with a fleshy 
green or corolla like perianth; while 
the Triuridales, comprising a single 
family, consist mostly of saprophytic 
herbs, or plants deriving their sub- 
sistence from decaying vegetable 
matter, and thus wholly destitute of 
leaves. < 
Fic. 12.—Zones of aquatic vegetation. In the center pond lilies; at the edge smart- 
weed; farther back cat-tails, blue flags, sweet flags and sedges; still farther back soft 
turf with grass, moss, sedges and milkweed. (From MacMillan’s Minnesota Plant Life, by 
- courtesy of the author. 
