VI. PLANTiE WRIGHTIAN^. 41 



Petalostemon exile (sp. nov.): annum, glabrum ; caule erecto tenui simplici 

 vel simpliciter lamoso ; foliolis 3 raro 5 linearibus mucronato-apiculatis parce 

 punctatis, imparl lateralibus longiore ; spica longe pedunculata cylindrica densa ; 

 bracteis ovatis subulato-acuminatis subvillosis floiibus pavillo brevioribus persisten- 

 tibus ; calyce villosissimo, dentibus setaceo-subulatis tubo aequilongis pctala rosea 

 subaequautibus. — Hill-sides, near Santa Cruz, Sonora, Sept. ; also near the copper 

 mines, New Mexico, Oct. (995.) — Stems 6 to 14 inches high, very slender. 

 Lateral leaflets 4 to G lines, the terminal one 9-18 lines in lengtli, a line or less in 

 width, plane, glabrous, or Avith a few minute hairs. Spike an inch or an inch and a 

 half long in fruit, 3 lines thick ; the lowest bracts broader and less subulatejiointed 

 than the upper, and nearly glabrous ; the others are arachnoid-villous, especially the 

 margins. Calyx 2 lines long. Petals very small, oval, nearly similar. Stamens 5. 

 — The genus Dalea scarcely occurs east of the Mississippi ; and even in Arkansas 

 and Eastern Texas there are ten Petalostemons to five Daleas. But as we proceed 

 westward and southward, the former genus disappears, and the species of the latter 

 largely increase. Petalostemon violaceum, the most widely diffused species, alone 

 reaches the northern frontiers of New Mexico ; the present species comes from 

 farther south, and is the only one known to occur in Mexico. 



Melilotus parviflora, Desf. Near El Paso, and in Sonora ; naturalized. (996.) 

 Medicago SATIVA, jLm«. Fields, El Paso and San Elisario ; introduced. (13.56.) 

 Trifolium involucratum, WiUil. ; Benth. PI. Hartw. no. 54 ; Gray, PI. Fcndl. 

 p. 3.3. Valley of the Sierra de los Animos, New Mexico, on the borders of springs ; 

 Oct. (997.) — The margin of the leaflets is fringed with as long setaceous teeth 

 as in any form of T. fimbriatum, Lindl. ; but the calyx-teeth are much longer than 

 the tube. 



^- ^- -I- Herbaceffi, glabra; ; foliis multijugis ; spicis elongatis alopecuroideis. 



Perennis, microphylla : corolla flava. D. l^vigata. 



Annua : corolla alba roseo tincta. D. alopecuroides. 

 H- H- 4- ^- Herbacese vel suffVuticosw, pubescentes, toinentosa?, vel sericeoe. 



Spica densissima, recta ; floribus albis. D. albiflora. 

 Spica densissima, crassa, villosissima ; floribus flavis vel purpurels. 

 Foliola appresso-sericea, 2-4-juga, raro pinnato-trifoliolata. 



Spica longissime pedunculata, e caule virgato erecto. D. aurea. 



Spica breviter pedunculata : caules ramosi : foliola oblonga obtusa. D. nana. 



Spica sessilis : foliola lanceolata acuta. D. W rightii. 



Foliola appresso-sericea, tria, digitata ! D. Jamesii. 

 Foliola laxc villosa, 4- 8-juga. 



Glanduloso-tuberculata : spica crassa, bracteis pubescentibus. D. lachnostachys. 



Villoso-canescens, humilis ; bracteis villosissimis. D. mollis. 

 Spica laxiuscula ; corolla pulchre purpurea. 



Tomentosa; caulibus diffusis ramosissimis. ^- lanata. 



Sericea ; caulibus strictis simpliciusculis. "• " 'slizeni. 

 * * » Calyx- pulcscciis rcl canescens, dentibus bi-enhus. (Frutcsccntes.) 



Foliola 7 - 13, sericeo-argcntea : corolla flavo-purpurea. D- argyr^a. 



Foliola 5-7, glabella : corolla alb^u P- leucostachys. 



Foliola 1 - 3, linearia : corolla pulcbre violacea. D. scoi'aria. 



» * * » Calyx nisi ad margines glaber ; dentibus brevibus. - D. FRnxESCENS. 



