10 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



[VOL. 10 



the original area became divided, and that since then a parallel evolution has 

 proceeded without appreciable interchange. 

 Type species : Xyris indica Linnaeus. 



Key to the Sections of Xyris 



1. Placentae parietal; funicles short. 



1. Placenta basal; funicles mostly elongate. 



I. Section Xyris. 



I. Section Xyris. 

 II. Section Nematopus. 



Key to the Species of Section Xyris 



1. Dorsal area uniform or with a very obscure median line; scapes 1-2-costate; seeds 



broadly ellipsoid, biapiculate with 2 minute black appendages. 1. X. caroliniana. 



1. Dorsal area with a strong median line; scapes 2-9-costate; seeds irregularly cylindric 

 or fusiform with a single large pale appendage. 

 2. Ehizomes lacking; leaves even or finely nerved, 1-5 mm wide. 2. X. fallax. 



2. Ehizomes present ; leaves coarsely and laxly nerved, 8 mm wide. 3. X. erythema. 



1. Xyris caroliniana Walter, Flora Carol. 69. 1788. 



The commonest and most widespread, and most variable and plastic species 

 of Xyris in the Western Hemisphere. Two ill-defined varieties may be recognized. 



Xyris caroliniana Walter var. caroliniana. 



X. jupicai L. C. Eichard, Act. Soc. Hist. Nat. Paris 1: 106. 1792. 

 X. communis Kunth, Enum. PI. 4: 12. 1843. 



X. surinamensis Miquel, Linnaea 17: 58. 1843. non Sprengel, 1828. 

 X. difformis Chapman, Fl. So. U. S. 500. 1860. 

 X. elata Chapman, Fl. So. U. S. 501. 1860. 



Type. "Carolina," Walter. 



Distribution. Southeastern United States, Central America, the West Indies, 

 and South America to central Argentina and Uruguay : common. 



Xyris caroliniana Walter var. major (Martius) Idrobo & Smith, Caldasia 6: 

 199. /. 4. 1954. 



X. macrocephala Vahl, Enum. PI. 2: 204. 1805. 



X. laxifolia Martius, Flora 24 2 (Beibl. 2) : 58. 1841. 



X. laxifolia a major Martius, Flora 24 2 (Beibl. 2) : 58. 1841. 



X. sellowiana Kunth, Enum. PL 4: 13. 1843. 



Type. Brazil, Martius Hb. Fl. Bras. 547 (M, F photo 18669). 

 Distribution. Central America and the West Indies to central Argentina and 

 Uruguay ; common. 



Plants of var. major, as the name suggests, are merely qualitatively large 

 ecologic or genetic expressions of the species, in which the leaves and scapes are 

 longer and coarser, and the spikes conspicuously larger, reaching 35 mm in 

 length and 20 mm in diameter. No satisfactory " break" point can be reached 

 in separating the two varieties. 



