184 



THE CACTACEAE. 



KEY To SPECIES continued. 



A. Areoles spinifcrous; ribs not deeply crenate continued. 

 BB. Stems blight green. 



Margin of stems horny. 



Kilps of stem l)io;nl, thin, crenate 



Ribs of stem thick, scarcely crenate 



Margin of stem 1 ' not horny. 



Stigma-lobes branched or forked. 



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

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

 times) 



Stigma-lobes (so far as known) entire. 



Perianth-segments red or reddish puiple. 



Ribs thin, almost wing-like; perianth-segments linear 



Joint? angular, not winged; inner perianth-segments oblanceolate 

 Inner perianth-segments white. 



Scales on the ovary few and scattered 



Scales on the ovary brown, large, imbricated. 



Joint-angles strongly tubercled 



Joint-angles scarcely tubercled or not at all. 



Joints somewhat crenate 



Joints not crenate 



AA. Areoles without spines; ribs very deeply crenate 



7. II. undatus 



8. H. cubensis 



9. //. lemairei 



10. H. monacanlhus 



11. 77. stenopterus 



12. H. exlenstis 



.1,5. II. >ni/)i>leonis 

 . 14. 77. trigonus 



.15. H. triangular is 

 . 16. 77. anliguensis 

 .17. 77. calcaratus 



1. Hylocereus guatemalensis (Eiehlam). 



(.'i-rfiis trigonus guatemalensis Eiehlam, Monatsschr. Kakteenk. 21: 68. 1911. 



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

 cm. 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 all 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 Cercus trigonus 

 guatemalensis. 



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

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



FIG. 261. Joint ofH. 

 guatemalensis. Xo.5. 



2. Hylocereus purpusii (Weingart). 



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: Lowlands 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 Cercus purpusii. 



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



Ci-rfiis 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 

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



