1 84 



THE CACTACEAE. 



Key to Species — continued. 



A. Areoles spiniferous; ribs not deeply erenate — continued. 

 BB. Stems blight green. 



Margin of stems horny. 



Ribs of stem bioad, thin, erenate 7- H. undatus 



Ribs of stem thick, scarcely erenate 8. H. cubensis 



Margin of stems not horny. 



Stigma-lobes branched or forked. . . 

 Spines several ; margins of stem nearly straight ; stigma-lobes branched . . 9. H . lemairet 

 Spine one; margins of stem undulate; stigma-lobes forked 1 at least some- 

 times) 10. H. monacanthus 



Stigma-lobes (so far as known) entire. 



Perianth-segments red or reddish put pie. 



Ribs thin, almost wing-like; perianth-segments linear 11. H. stenopterus 



Joints angular, not winged; inner perianth-segments oblanceolate . . .12. H. extensus 

 Inner perianth-segments white. 



Scales on the ovary few and scattered. 13- H. napoleoms 



Scales on the ovarv brown, large, imbricated. 



Joint-angles strongly tubercled 14. ff. trigonus 



Joint-angles scarcelv tubercled or not at all. 



Joints somewhat erenate -. 15- B. triangularis 



Joints not erenate 16. H. antiguensis 



AA. Areoles without spines; ribs very deeply erenate 17. H. calcaratus 



1. Hylocereus guatemalensis (Eichlam). 



Cerens trigonus guatemalensis Eichlam, Monatsschr. Kakteenk. 21: 68. 1911. 

 Stems high-climbing, 3 to 5 meters long, stout, mostly 3 -angled, 2 to 7 

 em. broad, the basal parts often narrow or nearly terete; joints beautifully 

 glaucous or in time becoming more or less greenish; ribs low-undulate, the 

 margins horny, not at ah glaucous ; areoles 2 cm. apart or less ; spines 2 to 4, 2 to 

 3 mm. long, conic, dark, but on seedlings numerous and bristle-like ; flowers 3 

 dm. long; outer perianth-segments rose-colored, acuminate; inner perianth- 

 segments lanceolate, acute, white; style yellow, 7 mm. in diameter; stigma- 

 lobes 25, entire; fruit 6 to 7 cm. in diameter, covered with large scales; seeds 

 black. 



Type locality: Guatemala. 



Distribution: Guatemala. 



We have grown plants from seeds; the seedlings are erect, 4-angled, 

 the spines numerous, the bristles -white, the cotyledons 15 mm. long. 



Illustration: Monatsschr. Kakteenk. 23: 155, as Cerens trigonus 

 guatemalensis. 



Figure 261 shows a joint of a plant sent to the New York 

 Botanical Garden from Fiscal, Guatemala, by C. C. Deam. 



Fig. 26r. — Joint of H. 



2. Hylocereus purpusii (Weingart). guatemalensis. X0.5. 



Cereus purpusii Weingart, Monatsschr. Kakteenk. 19: 150. 1909. 

 Stems bluish, climbing, elongate, epiphytic; ribs 3 or 4, with horny margins only slightly 

 undulate; areoles small; spines 3 to 6, short; flowers large, 25 cm. long and nearly as broad when 

 fully expanded; outer perianth-segments narrow, purplish; middle perianth-segments golden; inner 

 perianth-segments broad, white except at the golden tips. 



Type locality: Near Tuxpan, Mexico. 

 Distribution: Lowdands of western Mexico. 



We have grown this plant but have not seen the flowers, our description of them being 

 founded on that of Mr. "Weingart. 



Illustrations: Monatsschr. Kakteenk. 22: 26, 27, both as Cerens purpusii. 



3. Hylocereus ocamponis (.Salm-Dyck) Britton and Rose, Contr. U. S. Xat. Herb. 12: 429. 1909. 



Cereus ocamponis Salm-Dyck, Cact. Hort. Dyck. 1849. 220. 1850. 

 Stems strongly 3-angled, at first bright green, soon glaucous, dull bluish green in age; ribs rather 

 deeply undulate, their margins with a horny, brown border; areoles 2 to 4 cm. apart, borne near the 



