XYR1DACEAE. 235 



the testa reticulated ; embryo at the apex of the mealy endosperm. The 

 family consists of the following genus : 



i. MAYACA Aubl. 



Characters of the family. [Aboriginal name of these plants in Guiana.] Abou* 

 7 species, natives of warm and tropical America. Only the following occurs in the 

 United States : 



i. Mayaca Aubl&ti Michx. MAYACA. (I. F.f. 892.) Stems tufted, 7-55 

 cm. long, little branched. Leaves densely clothing the stem and widely spreading, 

 linear-lanceolate, translucent, 4-6 mm. long, about 0.5 mm. wide; peduncles 4-1.^ 

 mm. long, very slender, recurved in fruit ; flowers 6-8 mm. broad, lateral, rarely 

 more than one on each branch ; capsule oblong-oval, about as long as the sepals, 

 tipped until dehiscence by the subulate style. In fresh water pools and streams, 

 Va. to Ha. and Tex. May-July. 



Family 2. XYRIDACEAE Lindi. 



Yellow-eyed Grass Family. 



Tufted herbs, with basal narrow equitant commonly 2-ranked leaves, 

 and erect simple leafless scapes. Flowers perfect, mostly yellow, nearly 

 or quite regular, solitary and sessile in the axils of coriaceous imbricated 

 bracts (scales), forming terminal heads. Sepals 3, the two lateral ones 

 small, keeled, persistent, the other one larger, membranous (wanting in 

 the South American genus Abolboda). Corolla inferior, with a narrow 

 tube and 3 spreading lobes. Stamens 3, inserted on the corolla, usually 

 alternating with as many plumose or bearded staminodia. Ovary sessile, 

 i -celled or incompletely 3-celled ; ovules on 3 parietal placentae, "ortho- 

 tropous ; style terminal (unappendaged in Xyris, in Abolboda appendaged 

 at the base), 3-branched above ; stigmas apical. Fruit an oblong 3-valved 

 capsule. Seed-coat longitudinally striate. Embryo apical. Endosperm 

 mealy or somewhat fleshy. Two genera, comprising some 60 species, 

 mostly of tropical distribution in both the Old World and the New. 



i. XYRIS L. (See Appendix.) 



Characters of the family as given above. [Greek name for some plant with 

 2-edged leaves.] 



Besides the following species there are some 9 others in the southern United States. 

 Lateral sepals wingless, the keel fringed with short hairs. i. X.flexuosa. 



Lateral sepals winged, the keel fimbriate or lacerate. 



Scapes not bulbous-thickened at the base ; leaves flat or but slightly twisted. 

 Lateral sepals about as long as the bracts, their keels lacerate. 



Head oblong, 3-6 mm. long ; northern. 2. X, montana. 



Head oval or ovoid, 6-16 mm. long ; southern. 



Keel of lateral sepals lacerate to below the middle. 3. X. macrocephala. 

 Keel of lateral sepals lacerate only above the middle. 



4. X. Caroliniana. 

 Lateral sepals longer than the bracts, their keels long-fimbriate. 



5. X.fimbriata. 

 Scapes conspicuously bulbous-thickened at the base ; leaves spirally twisted. 



6. X. arenicola. 



1. Xyris flexuosa Muhl. SLENDER YELLOW-EYED GRASS. (I. F. f. 893,) 

 Scapes slender, straight or sometimes slightly twisted, 1-4.5 dm. tall, 2-edged 

 above, bulbous-thickened at the base. Leaves flat or becoming twisted when old, 

 2-15 cm. long, 1-3 mm. wide ; head globose, or short-oblong, obtuse, 6-8 mm. 

 high ; bracts broadly oval or slightly obovate, entire, or somewhat lacerate at the 

 apex ; lateral sepals linear, about as long as the bracts, curved, fringed with short 

 hairs on the wingless keel ; flowers 6-8 mm. broad. In bogs, Me. to Minn., Ga. 

 and Tex. July-Sept. 



2, Xyris montana H. Ries. NORTHERN YELLOW-EYED GRASS. (I. F. 

 894.) Scapes very slender, straight or slightly twisted, 2-edged above, 5-30011. 



