82 GRAMINEAE 



GRAMINEAE 1 . 



By A. S. HITCHCOCK, 

 Systematic Agrostologist, U. S. Department of Agriculture. 



Mostly herbaceous plants, with usualty hollow stems (culms) closed at the 

 nodes, and 2-ranked leaves. Leaves consisting of two parts, the sheath and the 

 blade, the sheath enveloping the culm with the margins usually overlapping, 

 the blade with parallel veins, usually narrowly linear; at the junction of the 

 sheath and blade on the inside, a membranaceous or hyaline appendage, the 

 ligule. Inflorescence paniculate or contracted into racemes or spikes, the 

 branches usually bractless. Flowers usually perfect, small, without a distinct 

 perianth, arranged in spikelets consisting of a shortened axis (rachilla) and 2 

 to many distichous bracts, the lowest pair (the glumes) empty, each succeed- 

 ing bract (the lemma) including a single flower and, with its back to the 

 rachilla, a 2-nerved bract or prophyllum (the palea), the flower and its lemma 

 and palea being called the floret. At the base of the flower, between it and the 

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

 the flower and the palea. Stamens usually 3, with delicate filaments and 

 2-celled versatile anthers. Pistil 1, with a 1- celled 1-ovuled ovary, usually 2 

 styles and usually 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 stems are woody in bamboos (cultivated in California for ornament) 

 and in a few other groups, and are solid in corn, sorghum and some other 

 large grasses. The sheath is sometimes grown together at the margins, as in 

 Melica and Glyceria. The blade in some tropical grasses is broad or even cor- 

 date, and there is occasionally a short petiole above the sheath. The flowers 

 may be monoecious as in the cultivated corn, or dioecious, as in Distichlis and 

 Monanthochloe. One or both of the glumes may be wanting, as in Paspalum 

 and Leersia. The lemma may be sterile, that is, it may contain only stamens, 

 or only the palea, or the latter may be reduced or wanting, or the lemma itself 

 may be variously modified or reduced, as in the upper florets of Melica, or 

 Bouteloua. The stamens are rarely 1, 2, or 6, and the styles are rarely 1 or 3. 

 The seed is free from the thin pericarp in Sporobolus, Eleusine, Crypsis and 

 Heleochloa. A large family of about 500 genera distributed throughout the 



'This article is published with the permission of the Secretary of Agriculture. 

 Unless otherwise stated the specimens cited are in the National Herbarium. Headers are 

 especially cautioned against being misled by discrepancies in the numbers, as it occasionally 

 happens that a specimen in the National Herbarium under a given number differs from speci- 

 mens in other herbaria under the same number. Furthermore there are some irregularities in 

 the numbering of certain series of specimens in the National Herbarium. Davy & Blasdale's 

 numbers are often duplicated on specimens credited to Davy. Specimens collected by Heller 

 & Brown were also distributed as collected by Heller. The data for many specimens collected 

 by Davy in Monterey Co. and elsewhere are placed on labels with a printed heading, ' ' Del 

 Norte, Humboldt and Mendocino Counties." This is misleading only when the locality is 

 not given, or is obscure or local, or is not to be found in the atlases. It is to be regretted 

 that collectors have so often omitted the habitat from the labels. The keys to tribes and 

 genera are based upon the groups as represented in California. Jepson's Flora of Western 

 Middle California, second edition, 1911, has not been cited under references except when it 

 differs from the first. A. S. HITCHCOCK. 



