POACEAE. 5 



FAMILY 1. ELODEACEAE. TAPE-GRASS FAMILY. 



Plants with leafy stems, or leaves basal, often greatly elongate. Gynoe- 

 cium 2-5-carpellary, the ovary 1-celled. 



1. HALOPHILA Thouars. Marine herbs. Leaves opposite or whorled. 

 Flowers dioecious, the staminate pedicelled, the pistillate sessile in the spathes. 

 Fruit included in the spathe. 



1. H. Engelmannii Aschers. Leaf -blades linear, oblong or oblanceolate, 1-3 cm. 

 long, sharply serrulate, 3-nerved, sessile: flowers and fruits not seen. -Shallow 

 water, U. S. keys, U. keys, L. keys. [E. K.] (Bah.) 



FAMILY 2. HYDROCHAEITACEAE. FROG'S-BIT FAMILY. 



Plants .with leaves in clusters on the rootstocks. Gynoecium 6-12- 

 carpellary, the ovary 6-12-celled. 



1. THAJjASSIA Banks. Marine herbs. Leaves mere strap-like blades. 

 Flowers dioecious, on scapes arising from the leaf -clusters ; the staminate dis- 

 tinctly pedicelled, with 3 petaloid sepals, and 9 stamens with very short fila- 

 ments and long anthers; the pistillate flowers nearly sessile. Fruit rugose, 

 echinate or mammillate, valvate. 



1. T. testudinum Koenig & Sims. Leaves 2-5 together; blades linear, 5-30 cm. 

 long, about 1 cm. wide or less, the bases persistent on the short stems: sepals 

 oblong, 10-12 mm. long: anthers 8 mm. long: fruits erect, densely mammillate. 

 Shallow water, U. S. keys, U. keys, L. keys. [E. K.] (Ber., Bah., Cuba, 

 Ant.) TURTLE-GRASS. 



Order POALES. 



Mostly perennial caulescent or acaulescent plants, known as grasses 

 and sedges. Stems sometimes conspicuously jointed. Leaves alternate, 

 mostly sheathing at the base : blades usually narrow and elongate, entire or 

 nearly so. Flowers variously disposed in a simple or compound inflores- 

 cence, perfect or rarely monoecious or dioecious, incomplete, inconspicuous, 

 borne in the axils of chaffy bracts or scales (glumes). Fruit a caryopsis 

 (grain) or an achene, or rarely a nut, or baccate. 



Leaves 2-ranked, their sheaths with un-united margins : stem mostly hollow : fruit a 

 grain (caryopsis). Fam. 1. POACEAE. 



Leaves 3-ranked, their sheaths with united margins : stem 



solid : fruit an achene. Fam. 2. CYPERACEAE. 



FAMILY 1. POACEAE. GRASS FAMILY. 



Annual or perennial herbs, or rarely shrub-like or tree-like plants. 

 Stems (culms) usually hollow, the nodes closed. Leaves with a scarious 

 ring (ligule) at the sheath-orifice. Inflorescence of spikes, racemes, or pani- 

 cles. Spikelets of 2-many 2-ranked imbricate bracts (scales), the upper 

 ones bearing a flower surrounded by a bract-like organ (palet) which is 

 placed with its back to the axis (rachilla), which is often thickened and 

 appears as a hard projection (callus) at the base of the scale. Flowers 

 perfect, staminate, or pistillate. Stamens 1-6, rarely more, usually 3. 

 Fruit sometimes nut -like. 



