45° 



MAYACACEAE. 



Vol. I. 



Family 14. MAYACACEAE Walp. Ann. 3 : 662. 1853. 



Mayaca Family. 

 Slender branching aquatic moss-like herbs, with linear sessile i-nerved entire 

 soft leaves, notched at the apex. Flowers solitary, peduncled, white, perfect, 

 and regular, the peduncles bracted at the base. Perianth persistent, consisting 

 of 3 lanceolate green herbaceous sepals and 3 obovate white spreading petals. 

 Stamens 3, hypogynous, alternate with the petals; filaments filiform; anthers 

 oblong, somewhat 4-sided, 2-celled. Ovary superior, sessile, i-celled with 3 

 parietal placentae; ovules several or numerous, orthotropous ; style filiform; 

 stigmas terminal, entire or with 3 short lobes. Capsule 1 -celled, 3-valved. Seeds 

 ovoid or globose, the testa reticulated ; embryo at the apex of the mealy endosperm. 



The family consists of the following genus. 



i. MAYACA Aubl. PI. Guian. 1 : 42. 1775. 



About 7 species known, natives of warm and tropical 

 America. Only 2 species in the United States. Type 

 species : Mayaca fiuviatilis Aubl. 



[Aboriginal name of these plants in Guiana.] 



i. Mayaca Aubleti Michx. Mayaca. 

 Fig. 1 131. 



Mayaca Aubleti Michx. Fl. Bor. Am. 1 : 26. 1803. 

 Mayaca Michauxii Schott & Endl. Melet. 1 : 24. 1832. 



Stems tufted, 3'— 15' long, usually little branched. 

 Leaves densely clothing the stem and widely spread- 

 ing, linear-lanceolate, translucent, 2"-$" long, about 

 I" wide; peduncles 2"-6" long, very slender, re- 

 curved in fruit; flowers 3"-4" broad, axillary, but 

 borne near the ends of branches, lateral, rarely 

 more than one on each branch; capsule oblong- 

 oval, about as long as the sepals, tipped until de- 

 hiscence by the subulate style. 



In fresh water pools and streams, southeastern Vir- 

 ginia to Florida and Texas. May-July. 



Family 15. XYRIDACEAE Lindl. Nat. Syst. Ed. 2, 388. 1836. 

 Yellow-eyed Grass Family. 

 Perennial or annual 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 ovoid globose or cylindric 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 numerous or few, 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 some- 

 what fleshy. 



Two genera, Xyris L. and Abolboda H. & B., comprising some 60 species, mostly of tropical 

 distribution in both the Old World and the New. 



1. XYRIS L. Sp. PI. 42. 1753. 



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. Type 

 species : Xyris indica L. 



Lateral sepals wingless, the keel fringed with short hairs. 1. X.fiexuosa. 



Lateral sepals winged, the keel erose, fimbriate or lacerate. 



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



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

 Heads ovoid ; bracts relatively few and in few series. 

 Leaves linear or tapering from the base to the apex. 



