36 H ydrocharitaceae 
HYDROCHARITACEAE (Vallisneriaceae) 
Water-weed Family 
Perennial, submerged (ours) or floating, with rhizomes or stolons, sometimes acaules- 
cent (not ours). Leaves opposite or whorled (in ours), or fascicled. Flowers of |—3 
usually more or less united bracts, enclosed in a spathe, dioicous or polygamous. Calyx 
in the pistillate flowers usually well developed, usually tubular; in the staminate flowers 
often short or obsolete. Perianth regular or nearly so; sepals 3; petals 3; often rudi- 
mentary or wanting. Stamens 3—-12; filaments short or none, sometimes monadelphous. 
Pistil 1, compound; ovaries |-celled, with 2—5 but usually 3 parietal placentae. Fruit 
indehiscent, maturing under water. Seeds few—many. 
PHILOTRIA (Elodea, Anacharis) WATER-WEED 
Stem elongated. Leaves sessile, pellucid, 1-veined, oblong or ovate-oblong, usually 
obtuse, in ours 510 mm. long and 2—4 mm. wide, margin usually minutely denticulate 
or serrulate. Flowers rarely perfect. Staminate flowers solitary or in 3’s, sessile or nearly 
so, early separating from the plant and floating on the water; stamens 9. Pistillate flowers 
solitary, sessile, calyx prolonged as a long slender tube; stamens none, or 3 rudiments. 
Fruit linear or lance-linear; seeds 3—21. (Gk. phyllon—leaf, treis—3; leaves are often 
in O.s.)e Wacke P. canadensis Brit. ; 
GRAMINACEAE (Poaceae) Grass Family 
Herbs (ours), annual or perennial; stems terete, usually hollow, their joints closed. 
Leaves sheathing, with scarious ring (ligule) where blade joins sheath; sheath usually 
split to base on side opposite the blade. Inflorescence paniculate or racemose or spicate 
or head-like, but the elements of the inflorescence composed of flower-groups (spikelets) 
of | to many flowers. Spikelets composed of O—2 basal flowerless bracts (glumes), 
above which are other bracts usually in pairs (the outer—lemma, the inner—palet) and 
each pair enclosing a flower or an abortive one. Lemma and glume often awned. Palet 
with back to axis (rachilla) of spikelet, opposite its lemma and often rolled up in it. 
Stamens 1—6, usually 3; anthers versatile. Ovary |-celled, 1-ovuled; styles 1—3, 
usually 2 and lateral; stigmas plumose or hairy. Fruit a grain (ours). 
A. Spikelets 1-flowered, rarely 2-flowered, terete or dorsally compressed (laterally in 
Oryzeae), falling entire and singly or in groups or together with joints of the rachis; 
imperfect flower below in the 2-flowered spikelets; rachilla articulate below the 
glumes, not produced beyond the flowers. 
B. Glumes 1—2; spikelets terete or dorsally compressed, |—2-flowered. 
C. Glumes indurated; lemma and palet of fertile flower hyaline; stamen 1. 
ANDROPOGONEAE (p. 37) 
CC. Glumes membranous; lemma and palet of fertile flower indurated; stamens 
3. PANICEAE (p. 37) 
BB. Glumes none; spikelets much laterally compressed, 1-flowered. 
ORYZEAE (p. 39) 
AA. Spikelets | to many flowered, more or less laterally compressed; rachilla and 
glumes remaining after the grain has fallen; imperfect flower uppermost (except 
Hierochloe) in spikelets of 2 or more flowers; rachilla usually articulate above the 
flowers. 
D. Spikelets not in rows. 
E. Spikelets 1-flowered; in racemes or spikes or panicles. 
F. Spikelets with 2 sterile lemmas just above the glumes. PHALAREAE (p. 39) 
