The families of flowering plants Habit and leaf form. Herbs;
laticiferous. Perennial; with a basal aggregation of leaves;
rhizomatous (monopodial). Hydrophytic to helophytic. Leaves
emergent. Leaves alternate; distichous (at least in origin);
petiolate, or sessile; sheathing. Leaf sheaths not tubular; with
free margins. Leaves simple. Lamina entire; linear (more or less
triquetrous, twisted); parallel-veined. Axillary scales present.
Lamina margins entire. General anatomy. Plants without
laticifers (but with laticiferous canals). Accumulated starch
exclusively pteridophyte type. Leaf anatomy. Stomata present;
paracytic. Guard-cells not grass type. Lamina with secretory
cavities. Secretory cavities containing latex; schizogenous. The
mesophyll containing calcium oxalate crystals, or without
calcium oxalate crystals (? no raphides). Vessels absent. Stem
anatomy. Secretory cavities present; with latex. Secondary
thickening absent. Xylem without vessels. Sieve-tube plastids
P-type; type II. Root anatomy. Root xyl