96 Contributions from the Gray Herbarium 



coma). Aril 2-lobed, appressed, 0.5 nun. Long. HBK. Nov. Gen. 

 v. 397. t. 509 (1821); Chod. Monog. ii. 180. t. 21. f. 37-38 (1893). 

 P. Nelsonii Rose, Contr. U. S. Nat. Herb. x. 122. t. 38 (1906). 

 Divisible into two color forms. 



Forma typica. Florcs purpurei. Vera Cruz: dry meadows, 

 Zacuapan, Aug. 1906, Purpus 2074 (G); Mirador, Liebmann 15 

 (K). Mexico without locality: Haenke G). British Honduras: 

 open ground, near Manatee Lagoon, 27 Sept. 1905, M. E. Peck 147 

 (G). Honduras: Stann Creek, 13 April, Rev. J. Robertson 194 (B). 



Forma leucanthema. Flores albi. Vera Cruz : Salina Cruz, 

 22 Dec. 1898, C. C. Deam 99 (type: G). T. 2. Fig. 72, 72a. 

 Deam 99 ,in addition to being white-flowered, differs in its consider- 

 ably smaller flowers (the minima in the measurements above) , but 

 agrees in all technical characters with Purpus 2074. P. variabilis 

 has been confused with P. trichosperma L., but differs in its longer 

 aril-lobes, those of P. trichosperma being very minute. 



Ser. e. Tenues Chod. Slender annuals, the linear leaves alter- 

 nate throughout or sometimes opposite or whorled below; racemes 

 very slender, the flowers tiny; seed glabrous or sparsely short- 

 pubescent with straight hairs, never comose. Polygala sect. 

 Orthopolygala subsect. I. H. Tenues Chod. Monog. ii. 214 (1893). 



a. Seed glabrous; aril very minute, b. 



b. Racemes white, very dense; bracts persistent 119. P. gracillima. 



b. Racemes looser, pink; bracts deciduous 120. P. decidua. 



a. Seed pubescent; aril evident, c. 



c. Plant glabrous, d. 



d. Aril tiny, barely 2-lobed, about -^ as long as seed . . . 121. P. paludosa. 



d. Aril | as long as seed 122. P. gracilis. 



c. Plant finely stipitate-glandular; aril |- as long as seed 



123. P. paniculata. 



119. P. gracillima Wats. Annual, erect, branched above, 9-21 

 cm. high, the almost filiform stems glabrous, not angled. Leaves 

 (except 1-2 whorls of 3 obovate leaves at extreme base, 3-3.5 mm. 

 long, 1.5-2 mm. wide) scattered, ascending, linear, cuspidate, 

 gland-dotted, glabrous, subsessile, 2-7 mm. long, 0.3-0.6 mm. wide. 

 Racemes very slenderly conic-cylindric, dense, 6-22 (axis becoming 

 28) mm. long, 2-2.6 mm. thick, on peduncles 9-27 mm. long; 

 pedicels 0.2 mm. long; bracts lance-subulate, bearing a large gland 

 at base, 0.8 mm. long, spreading-ascending, persistent. Flowers 

 white, 1.3 mm. long. Upper sepal oval, obtuse, lower ovate, acute, 

 0.6 mm. long. Wings oblong-oval, rounded at apex, short-clawed 



