TAPE-GRASS FAMILY 



103 



Family 9. VALLISNERIACEAE. 



Tape-grass Family 

 Submerged or floating-, fresh water or marine, perennial herbaceous plants, the 

 leaves various. Flowers regular, mostly dioecious, appearing from an involucre 

 or spathe of 1-3 bracts or leaves. Perianth 3-6-parted, the segments either all 

 petioled or the outer small and herbaceous, the tube adherent to the ovarv at its 

 base in the pistillate flowers. Stamens 3-12. Anthers 2-celled. Ovary l-celled 

 with 3 parietal placentae. Styles 3, with entire or 2-cleft stigmas. Ovules anatro- 

 pous or orthotropous. Fruit maturing under water, indehiscent. Seeds numer- 

 ous, without endosperm. 



A family of about 6 genera and 25 species. 



1. PHILOTRIA Raf. Am. Month. Mag. 2: 175. 1818. 

 [Elodea Michx. Fl. Bor. Am. 1 : 20. 1803. not Elodes Adans. 1763.] 

 Stems submerged, elongated, branching, leafy. Leaves opposite or whorled, usually 

 crowded. 1 -nerved, pellucid, minutely serrulate or entire. Flowers dioecious or polygamous, 

 arising from an ovoid or tubular 2-cleft spathe. Staminate flowers solitary, rarely in threes, 

 sessile or nearly so. early separating from the plant and floating on the surface of the water ; 

 sepals and petals 3, or the latter sometimes wanting ; stamens 9, in two series, the outer of 

 6 and the inner of 3 stamens. Pistillate flowers solitary, sessile, the perianth-tube prolonged 

 into a long slender pedicel-like tube ; sepals and petals 3 ; stamens none or represented by 3 

 rudimentary filaments. Hermaphrodite flowers like the pistillate, but with 3-9 stamens. 

 Fruit linear or lanceolate-linear. [Greek, referring to the leaves, which are often in whorls 

 of three.] 



An American genus of about 10 species. Type species, Elodea canadensis Michx. 



1. Philotria planchonii ( Casp. ) Rydb. 



Rockv Mountain Waterweed. 



Fig. 217. 



Anacharis canadensis Planch. Ann. Mag. Nat. Hist. II. 1 : 86. 

 1848, mainly. 



Elodea planchonii Casp. Jahrb. Wiss. Bot. 1: 408. 1858. 



Dioecious aquatic herb, with slender stems, 1-20 cm. 

 long. Leaves in threes or the lower opposite, sessile, 

 oblong to linear. 7-15 mm. long. 1-2 mm. wide, acute 

 or acutish ; spathe of the staminate flowers obovoid- 

 clavate, nearly 1 cm. long, on a peduncle 5-10 mm. 

 long; staminate flowers short-pediceled; sepals elliptic, 

 5 mm. long; petals wanting; stamens 9; anthers ob- 

 long, 3-4 mm. long, subsessile ; spathe of the pistillate 

 flowers linear or lanceolate-linear, sessile. 2-cleft at the 

 apex ; perianth-tube slender. 3-5 cm. long ; sepals and 

 petals linear, about 3 mm. long; stigmas 3. linear; sta- 

 mens none. 



In lakes and ponds. Canadian Zone; Saskatchewan to Wash- 

 ington, south to Colorado, Nevada, and Truckee, California. 

 Type locality: Saskatchewan. 



Family 10. POACEAE.* 

 Grass Family. 



. Herbs or rarely woody plants, with usually hollow stems (culms) closed at the 

 nodes, and 2-ranked parallel-veined leaves, these consisting of 2 parts, a lower, 

 the sheath, enveloping the culm, its margins overlapping or sometimes grown 

 together, an upper, the blade, usually flat,- and, between the two on the inside, a 

 membranaceous hyaline or hairy appendage (the ligule). Flowers perfect (rarely 

 unisexual), small, with no distinct perianth, arranged in spikelets consisting of a 

 shortened axis (rachilla) and 2 to many 2-ranked bracts, the lowest 2 being empty 

 (the glumes, rarely 1 or both of these obsolete), the 1 or more succeeding ones 

 (lemmas) bearing in their axils a single flower, and, between the flower and the 

 rachilla. a second 2-nerved bract (the palea) : stamens 1 to 6. usually 3. with very 

 delicate filaments and 2-celled anthers; pistil 1. with a l-celled l-ovuled-ovary, 2 



* Text contributed by Mr. A. S. Hitchcock, and published with the permission of the 

 Secretary of Agriculture. 



