86 GRAMINEAE (GRASS FAMILY) 



which are raised to the surface by sudden growth at the same time ; afterwards 

 the thread-form scapes (6-12 dm. long) coil up spirally, drawing the fruit 

 under water to ripen. (Named for Antonio Vallisneri, an early Italian botanist.) 

 1. V. spiralis L. Leaves thin, ribbon-like (0.3-2 m. long), obscurely serru- 

 late, obtuse, somewhat nerved and netted-veined. Common in slow waters, 

 N. S. to Fla., w. to Minn, and Tex. (Eurasia, Austr.) 



3. LIMNdBIUM Richard. AMERICAN FROG'S BIT 



Flowers dioecious (or monoecious ?), from sessile or somewhat peduncled 

 spathes ; the sterile spathe 1-leaved, producing about 3 long-pediceled flowers ; 

 the fertile 2-leaved, with a single short-pediceled flower. Calyx 3-parted or 

 -cleft ; sepals oblong-oval. Petals 3, oblong-linear. Filaments in the sterile 

 flowers entirely united in a central solid column, bearing 6-12 linear anthers at 

 unequal heights ; stamens in the fertile flowers 3-6 awl-shaped rudiments. 

 Ovary 6-9-celled, with as many placentae in the axis, forming an ovoid many- 

 seeded berry in fruit ; stigmas as many as the cells, but 2-parted, awl-shaped. 

 Floating in stagnant water and proliferous by runners. Leaves round-heart- 

 shaped, spongy-reticulated and purplish underneath. (Name from \tnv6pios, 

 living in pools.) 



1. L. Spdngia (Rose) Richard. Leaves 2.5-5 cm. long, faintly 5-nerved ; 

 peduncle of the sterile flower about 7.5 cm. long and filiform, of the fertile only 

 2.5 cm. long and stout. Stagnant water, N. J. to Fla. ; also L. Ont. to 111., 

 Mo. , and Tex. 



GRAMINEAE (GRASS FAMILY) 

 (REVISED BY A. S. HITCHCOCK) 



Herbs (shrubs or trees in Bambuseae) with usually hollow stems (culms) 

 closed at the nodes, and 2-ranked parallel-veined leaves these consisting of two 

 parts, the sheath and the blade, the sheath enveloping the culm with the mar- 

 gins overlapping or rarely grown together; at the junction of the sheath and 

 blade, on the inside, is a membranaceous hyaline or hairy appendage (the 

 ligule) rarely obsolete. Flowers perfect (rarely unisexual), very small, 

 without a distinct perianth, arranged in spikelets consisting of a short- 

 ened axis (rhachilla) and 2-many distichous bracts, the lowest two of which 

 (the glumes) are empty (rarely 1 or both obsolete) ; in the axil of each su^ci-ed- 

 ing bract (the lemma) is borne a single flower, subtended and usually enveloped 

 by a (normally) 2-nerved bract or prophyllum (the palea), with its back to the 

 rhachilla ; at the base of the flower, between it and the lemma, are usually 2 very 

 small hyaline scales (the lodicules), rarely a third lodicule between the flower 

 and the palea; stamens 3 (rarely 1,2, or 6), with very delicate filaments and 

 2-celled versatile anthers ; pistil, one, with a 1-celled 1-ovuled ovary, 2 (rarely 

 1 or 3) styles, and mostly plumose stigmas. Fruit a caryopsis with starchy endo- 

 sperm and a small embryo at the base on the side opposite the hilum. Grain 

 usually inclosed at maturity in the lemma and palea, free or adnate to the palea. 

 The lemma with its palea and flower constitute the floret. The lemma may l>e 

 variously modified ; and may be sterile or neuter, that is, containing a palea or 

 rudiment of one, without a flower, or empty ; or may itself be rudimentary (as 

 in some of the Chlorideae) ; in such cases the spikelet contains at least one per- 

 fect floret ; Ihe sterile or modified lemmas, one or more, above or below it. The 

 palea is rarely obsolete. Spikelets arranged in spikes, racemes, or panicles, the 

 branches of which are bractless. 



