990 



MISC. .PUBLICATION 200, U. S. DEFT. OF AGRICULTURE 



bergia wrightii; Panicum wrightianum ; 

 Sporobolv^ wrightii. 



Zois, Karl von (1756-1800). German 

 botanist. Zoysia. 



GLOSSARY 



Abortive. Imperfectly developed. 



Acuminate. Gradually tapering to a sharp 

 point. Compare acute. 



Acute. Sharp-pointed, but less tapering than 

 acuminate. 



Aggregate. Collected together in tufts, 

 groups, or bunches. Applied especially to 

 inflorescences. The racemes are aggregate 

 in several species of Andropogon. 



Annual. Within 1 year. Applied to grasses 

 which do not live more than 1 year. 

 Winter annual. A plant which germinates 

 in the fall, lives over winter, and produces 

 its seed the following spring, after which 

 it dies. 



Anthesis. The period during which a flower 

 is open. In grasses, when the lemma and 

 palea are expanded and the anthers and 

 stigmas are mature. 



Antrorse. Directed upwards or forwards. 

 Applied especially to scabrous or pubes- 

 cent stems, sheaths, awns, and so on. 

 Opposed to retrorse. 



Apiculate. Having a minute pointed tip. 

 Applied especially to fertile lemmas in 

 fruit, such as certain species of Eriochloa. 



Appressed. Lying against an organ. The 

 branches of an inflorescence may be 

 appressed to the main axis or the hairs on 

 a stem may be appressed to the surface. 



Aristate. Awned; provided ' ith a bristle at 

 the end or at the bac 1 or edge of an 

 organ. In grasses applies especially to the 

 awns at the end of the bracts of the spike- 

 let. Compare awn. Aristulate. Bearing a 

 short awn. 



Articulate. Jointed. Joined by a line of demar- 

 cation between two parts which at matur- 

 ity separate by a clean-cut scar. Certain 

 spikelets are articulate with the pedicel; 

 certain awns with the lemma. Articula- 

 tion. The point of union of two articulate 

 organs. 



Ascending. Sloping upward. Applied to stems 

 which curve upward from the base, to the 

 branches of an inflorescence which slope 

 upward at angle of about 40° to 70°, and 

 to other parts such as blades and hairs. 

 Compare appressed and spreading. 



Attenuate. Gradually narrowed to a slender 

 apex or base. 



Auricle. An ear. Applied to earlike lobes at 

 the base of blades and to the small lobes 

 at the summit of the sheath in Hordeae. 

 Auriculate. Provided with ears. 



Awn. A slender bristle at the end or on 

 the back or edge of an organ. In grasses 

 the awn is usually a continuation of the 

 midnerve (sometimes also of the lateral 

 nerves) of the glumes or lemmas, rarely of 

 the palea. 



Axil. The angle between an organ and its 

 axis. Applied especially to the angle 

 between a leaf and its stem and between 

 a branch or pedicel and its axis. Axillary. 

 Growing in an axil. 



Axis. The main stem of an inflorescence, 

 especially of a panicle. Compare rachis. 



Barbed. Furnished with retrorse projections. 

 Applied to the spines of Cenchrus. 



Beak. A hard point or projection. Applied to 

 seeds and fruits. 



Bearded. Furnished with long stiff hairs, as 

 the nodes of Andropogon barbinodis, the 

 callus of Stipa spartea, the throat of the 

 sheath of Sporobolus cryptandrus, and the 

 main axils of the panicle of Eragrostis 

 spectabilis. 



Bifid. Two-cleft or two-lobed, applied to the 

 summit of glumes, lemmas, and paleas. 

 The lemmas of Bromus are usually bifid 

 at apex. 



Blade. The part of a leaf above the sheath. 



Bract. The reduced leaves of the inflo- 

 rescence and upper part of a shoot. Com- 

 pare scale. 



Branch. A lateral stem. Applied to the foli- 

 age stems or culms, and to the lateral 

 stems of an inflorescence. Branchlet. A 

 branch of the second or higher order. In 

 open much-branched panicles the main 

 branches from the axis are branches of 

 the first order, the branchlets from these 

 are branches of the second order and so on. 



Bristle. A stiff slender appendage likened to 

 a hog's bristle. An awn is a kind of bristle. 

 In grasses the term is applied to the modi- 

 fied branchlets at the base of the spikelets 

 in Setaria and allied genera, and to the 

 prolongation of the rachis in Panicum, 

 sect. Paurochaetium, and a few other 

 groups. 



Bulb. A subterranean bud with fleshy scales 

 like the onion. The so-called bulbs of 

 grasses are corms (which see). Bulbous. 

 Swollen at base like a bulb or corm. Said 

 of the base of the stem of some species of 

 Melica, Phleum, Phalaris, and so on. 

 Bulblets. Small bulbs or corms. Applied 

 also to the proliferous buds in the inflo- 

 rescence of certain grasses, as Poa bulbosa. 

 proliferous forms of P. arctica, P. alpina. 

 and others. 



Callus. The indurate downward extension of 

 the mature lemma in Stipa, Aristida, and 

 some other genera. Morphologically, such 

 a callus is a part of the rachilla. In Hetero- 

 pogon and other Andropogoneae the callus 

 is an oblique part of the rachis which 

 extends downward from the spikelet. In 

 Chrysopogon the callus is a part of the 

 peduncle. The term callus is also applied 

 to the thickened lower joint and first 

 glume of Eriochloa (callus, a thickened 

 part). Callus hairs. The hairs at the base 

 of the floret of Calamagrostis and some 

 other genera. 



Canescent. Gray-pubescent or hairy. 



