22 Contributions from the Gray Herbarium 



longa. AJae ellipticae apice obtusae vel rotundatae l>asi late cune- 

 atae ad costam sparse puberulae 5.5 7 mm. Longae I mm. latae. 

 lYtala superiora obovata infra ciliata ad 3.8 mm. longa. Carina 

 glabra 4.5 1.8 nun. longa. Capsula deltoideo-ovata sursum mani- 

 feste angustata basi tnmcato-rotundata ciliata e1 in lateribua pu- 

 berula pilia brevibus patentibus emarginata .">.."> 7 mm. Longa 5-6 

 nun. lata. Semina cuneato-obovoidea breviter pilosa rugulosa 4 

 nun. longa 2.6 nun. lata. Arillus capitelliformis minutus ad 0.5 nun. 

 altus pilosus margine Bcarioso obsolete Guerrero: Acapulco, 

 Oct. 1894 Mar. 1895, Palmer 168 (type coll.: GK). T. 1. 

 FlG. 10. Very distinct in capsule and seed. Distributed as P. 

 americana Mill. 



Series i5. Obscurae, ser. nov. 1 Folia saepissime biformia, in- 

 feriora saepissime ovalia ad oblongo-ovalia superiora saepissime 

 longiora angustiora saepius linearia vel oblongo-linearia. Species 

 typica P. obscura Benth. 



a. Capsule more or less pubescent on sides at maturity, b. 

 b. Hairs of stem all incurved or appressed, c. 

 c. Aril minute, capitelliform, scarcely lobed, d. 



d. Flowers 4-5 mm. long 22. P. magdalenae. 



d. Flowers 6-7 mm. long 23. P. leptosperma. 



c. Aril larger, distinctly lobed or lobulate, e. 



e. Aril strongly 3-lobed, the lobes more or less ap- 



pressed, slender, /. 

 /. Flowers 4-5 mm. long 38. P. compacta. 



f. Flowers 6-7 mm. long 39. P. polymorphs. 



e. Aril veil-like, merely lobulate, g. 



g. Sepals and wings quickly deciduous 32. P. obscura. 



g. Upper sepal and wings rather persistent 34. P. Lozani. 



b. Hairs of stem (at least in part) wide-spreading, h. 



h. Leaves dimorphous (lower oval to oblong-oval, upper 

 oblong to lanceolate or linear), not reticulate; 



hairs all short and spreading 32.1. P. orthotricha. 



h. Leaves not dimorphous, linear-lanceolate, strongly 

 reticulate ; pubescence of short incurved and long 



patent hairs 31. P. retifolia. 



h. Leaves lanceolate to linear-lanceolate, subtomentose- 



velutinous 23. P. leptosperma. 



a. Capsule merely ciliate at maturity, i. 



i. Wings glabrous 20. P. Pavoni. 



i. Wings pubescent at least at base, j. 

 j. Aril small, the depth of the entire or merely denticulate- 

 lobulate scarious margin less than the height of the 

 corneous umbo, k. 



k. Pubescence of short widely spreading hairs 27.1. P. rectipilis. 



k. Hairs incurved or appressed, I. 



1 P. amphothrix (no. 42), P. chiapensis (no. 44), and P. trichoptera (no. 

 62) might be sought here. 



