no 



THE CACTACEAE. 



This ]>l:uit was collected for Cereus nichiintnts, but it is too tall and stout and has 

 spines and smaller (lowers. We have living specimens of this plant collected by 

 Scfior Porto, but they have not yet flowered in cultivation. 



16. WILCOXIA Britton and Rose, Contr. U. S. Nat. Herb. 12: 434. 1909. 



Plants usually low and weak, producing a cluster of dahlia-like roots; stems very slender, more 

 or less branched, the branches often only the diameter of a lead pencil; ribs few and low; spines of 

 all the areolcs similar; flowers diurnal, funnelform-campanulate, red or purple, large for the size of 

 the plant, only i from an areole, the tube rather short, its areoles bearing spines or bristles and wool; 

 arcoles of the ovary and fruit bearing spines or bristles and wool; seeds black; aril large, basal. 



Type species: Echinocereus poselgcri Lemaire. 



Four species, of Texas and Mexico, compose the genus as known. 



The type species has been included in Echinocereus, but its habit is very unlike that 

 genus, while the second and third species have been considered as belonging to Ccrcns 

 proper. 



The genus was named for General Timothy E- Wilcox, U. S. A., who for many years 

 has been an enthusiastic student of plants. 



KEY TO SPECIES. 



Areolcs on ovary and flower-tube bearing long bristle*. 



Stems puberulent I . W. viper ina 



Stems glabrous. 



Corolla about 5 cm. long; tube indefinite; seeds dull; spine-clusters approximate, 3 to 5 mm. apart. . 2. W. poselgeri 



Corolla 10 to 12 cm. long; tube definite; seeds shining; spine-clusters distant, 7 to 15 mm. apart. .3. W. slriata 



Areoles on ovary and lower part of flower-tube without long bristles 4. W. papillosa 



1. Wilcoxia viperina (Weber) Britton 

 and Rose, Contr. U. S. Nat. Herb. 

 16: 242. 1913. 



Cereus viperinus Weber in Gosselin, Bull. 

 Mus. Hist. Nat. Paris 10: 385. 1904. 



Stems elongated, branching, the 

 largest ones seen i cm. in diameter and 

 becoming spineless; branches densely 

 velvety-puberulent, 8 mm. in diameter 

 or less; ribs about 8, inconspicuous; 

 spines about 8, appressed, dark, about 

 5 mm. long; flowers red, about 3 cm. 

 long; spines of ovary and corolla-tube 

 black, bristle-like, intermixed with long 

 white wool. 



FIG. 163. Sections of stem of W. viperina. X 0.8. 



7"\/r Lhtility: Zapotitlan, Mexico. 



Distribution: Southern Puebla, 

 Mexico. 



The type of this species was col- 

 lected by L. Diguct and is now in the 





FIG. 164. Wilcoxia poselgeri. 



