312 PLANTiE NOV^ THURBERIAN J:. 



(Eutacece, including Zanthoxylacea) to which this anomalous genus has been provis- 

 ionally referred. The nearest relative of our plant, however, is found in the adjacent 

 small family of Simarubacece, namely in Castela, of Turpin ; — a genus formerly annexed 

 to the Ochnacece, but lately and more properly placed in Simaruhacece by Planchon, in 

 his revision of this group* Castela and the present genus, however, make a close ap- 

 proach to the Zanthoxylece, from which they mainly differ in the uniovulate carpels, the 

 dotless leaves, and the want of aromatic qualities. The habit of Holacantha is much the 

 same as that of Castela, except that the leaves, so far as known, are reduced to minute 

 and deciduous bracts : and the Quassia-like bitterness is also apparent in the bark, but 

 hardly in the wood. The essential floral difierences are merely the 7 - 8-merous (in- 

 stead of tetramerous) flowers, the thickened filaments in the male blossoms, and the 

 insertion of the ovule at a point so near the chalaza that this organ, as well as the 

 seed, is truly ascending instead of pendulous. The name chosen for the genus, from 

 oXo?, wholly, and aKuvOa, a thorn or thorn-bush, alludes to its perfectly spinous branch- 

 es throughout. 



GuAiACUM CoDLTERi (sp. uov.): stipulis parvis spinescentibus ; foliolis 3-5-jugis 

 lineari-oblongis mucronatis basi iuEequalibus ; capsula breviuscule stipitata 5-cocca, 

 coccis ovalibus dorso acute carinatis. — On hills between Rayon and Ures, Sonora ; 

 October, 1851. — The specimens bear ripe fruit only. They are said by Sir William 

 Hooker to accord with No. 779 of the Mexican collection of the late Dr. Coulter. The 

 petiole and rhachis together are an inch or less in length, and slightly pubescent when 

 young. Leaflets opposite, 6 to 8 lines long, minutely veiny. Flowers not seen. Cap- 

 sule half an inch in length, and of somewhat greater breadth, very deeply 5-lobed, or 

 by abortion -i-lobed, retuse at both ends, raised on a stipe of a line and a half in 

 length, the summit tipped with a short point ; the turgid lobes abruptly and sharply 

 keeled on the back. Cotyledons with their margins directed to the axis of the fruit. 



372. Astragalus (Phaca) Thurberi (sp. nov.): perennis, cinereo-pubescens, de- 

 mum glabratus ; caulibus subpedalibus striatis ; stipulis triangularibus basi imo petiolo 

 adnatis; foliolis 6-7-jugis carnosulis lineari-oblongis retusis ; pedunculis brevibus 

 cum spica 10 - 20-flora folio vix longioribus ; floribus ochroleucis 1 (3 lineas longis) 

 brevissime pedicellatis ; calycis pubescentis dentibus subulatis obtusiusculis tubo cam- 



* lu Lo7id. Jour. Bot., 5, p. 567. — Planchon attributes appendiculate filaments to Castela : but there are 

 certainly no squamulEB in C. Nicholsoni. 



