MANUAL OF THE GRASSES OF THE UNITED STATES 989 



Decumbent. Curved upward from a horizontal or inclined base. Said of stems 



or culms. 

 Decurrent. Extending down an organ below the insertion. Said especially of 



ligules decurrent on the margins of the sheath. 

 Dehiscence. Spontaneous opening of an organ, as the opening of anthers to let 



out the pollen. 

 Dense. Said of inflorescences in which the spikelets are crowded. The opposite 



of open or loose. Compare compact. 

 Depauperate. Reduced or undeveloped. Said especially of impoverished or 



dwarfed plants below the average size. 

 Diffuse. Open and much-branched. Said of panicles. 



Digitate. Several members arising from the summit of a support. Said espe- 

 cially of racemes or spikes from the summit of a peduncle, as in Digitaria and 



Cynodon. 

 Dioecious. Unisexual, the two kinds of flowers on separate plants, as in Buchloe. 

 Disarticulating. Separating at maturity. Compare articulate. 

 Distichous. Conspicuously two-ranked, as the leaves of Distichlis and Zea. 

 Divaricate. Widely and stiffly divergent as the branches of certain open panicles 



(e.g., Oryzopsis hymenoides). 

 Dorsal. Relating to the back of an organ. 

 Dorsiventral. With a distinct upper and lower surface. Said of shoots bearing 



broad flat blades in a horizontal position, the blades turned into the same plane. 

 Drooping. Erect to spreading at base but inclining downward above, as the 



branches of a panicle. 

 Ellipsoid. An elliptic solid. Said of the shape of panicles, spikelets, and fruits. 

 Elliptic. Shaped like an ellipse. Said of blades and other flat surfaces. 

 Elongate. Narrow, the length many times the width or thickness. 

 Emarginate. Notched at the apex. 

 Equitant. Astride. Said of approximate compressed-keeled sheaths or blades 



at the base of a culm that infold each other like the leaves of Iris. 

 Erose. Irregularly notched at apex as if gnawed. Said of glumes and lemmas. 

 Excurrent. Running beyond. The midnerve is excurrent from the lemma as 



an awn in many grasses. 

 Exserted. Protruding. The awns of some species of Calamagrostis are exserted, 



protruding beyond the spikelet. 

 Falcate. Scimiter-shaped, curved sidewise and flat, tapering upward. Said of 



certain asymmetric blades. 

 Fascicle. A little bundle or cluster. Said of clustered leaves, branches of a 



panicle, and spikes or racemes on an axis. 

 Ferrugineous, ferruginous. Rust colored. 

 Fertile. Capable of producing fruit, having pistils. A fertile floret may be pis- 



tillate or perfect. 

 Fibrillose. Furnished with fibers. Said especially of the old basal sheaths of 



some grasses. 

 Filiform. Threadlike. 



Fimbriate. Fringed, the hairs longer or coarser as compared with ciliate. 

 Flabellate. Fan-shaped. Said of the nerves of the lemmas of Anthochloa and 



the inflorescence of Miscanthus sinensis. 

 Flexuous. Bent alternately in opposite directions. 

 Floret. The lemma and palea with included flower (stamens and pistil) . Florets 



may be perfect, staminate, pistillate, neuter, sterile, and so on. 

 Folded. Conduplicate. Said chiefly of blades. 

 Fruit. The ripened pistil. In grasses the fruit is usually a caryopsis. The 



term fruit is also applied to the caryopsis and parts that may enclose it per- 

 manently at maturity. In Panicum the indurate fertile lemma and palea 



with the enclosed caryopsis is the fruit. In Cenchrus it is the entire bur. 

 Fusiform. Spindle-shaped. A solid that is terete in the middle and tapering 



toward each end. 

 Geniculate. Bent abruptly. Said of awns and of the lower nodes of the culm. 

 Gibbous. Swollen on one side as the glume of Sacciolepis. 

 Gland. A protuberance or depression, usually minute, that secretes, or appears 



to secrete a fluid. Glandular. Supplied with glands. The glands may be 



depressed as in Eragrostis cilianensis and Heteropogon melanocarpus. 

 Glaucous. Covered with a waxy coating that gives a blue-green color as in the 



leaf of the cabbage, and the bloom of the grape. 

 Glomerate. Collected in heads. 

 Glumes. The pair of bracts at the base of a spikelet. 



