HYLOCEREUS. 



I8 7 



7. Hylocereus undatus (Haworth) Britton and Rose in Britton, Flora Bermuda 256. 1918. 

 Cactus triangularis apliyllus Jacquin, Stirp. Amer. 152. 1763. 

 Cereus triangularis major De Candolle, Prodr. 3: 468. 1828. 

 Cereus undatus Haworth, Phil. Mag. 7: no. 1830. 

 Cereus tricostatus Gosselin, Bull. Soc. Bot. France 54: 664. 1907. 

 Hylocereus tricostatus Britton and Rose, Contr. U. S. Nat. Herb. 12: 429. 1909. 



Stem long, clambering over bushes and trees or creeping up the sides of walls; ribs mostly 3> 

 broad, thin, green; margin usually strongly undulate, more or less horny in age; areoles 3 to 4 cm- 

 apart; spines i to 3, small, 2 to 4 mm. long; flowers up to 29 cm. long or more; outer perianth-seg- 

 ments yellowish green, all turned back, some strongly reflexed; inner perianth-segments pure white, 

 erect, broad, oblanceolate, entire, with apiculate tips; filaments slender, cream-colored; stigma- 

 lobes as many as 24, slender, entire, cream-colored; style stout, 7 to 8 mm. in diameter, cream- 

 colored; fruit oblong, 10 to 12 cm in diameter, red, covered with large foliaceous scales, or nearly 

 smooth when mature, edible; seeds black. 



Type locality: China, evidently in cultivation. 



Distribution: Common throughout the tropics and subtropics; often found as an escape 

 and widely cultivated. 



This species has long been known in cultivation under the name of Cereus triangularis , 

 and it is to be regretted that the name triangularis can not be retained, but the plant which 

 Linnaeus described as Cactus triangularis came 

 from Jamaica. The latter is now well known 

 to botanists but it has never been much culti- 

 vated, while H. undatus is grown all over the 

 world and grows half -wild in all tropical coun- 

 tries. It is the best known of all the night- 

 blooming cereuses and has one of the largest 

 flowers. It makes a beautiful hedge plant ; in 

 Honolulu there is a hedge about Punahou 

 College which is half a mile long and is said to 

 produce 5,000 flowers in a single night. 



Cereus undatus was described by Haworth 

 from plants sent from China; he says it is 

 similar to C. triangularis, but twice as large. 

 Pfeiffer afterwards made it his variety major of 

 C. triangularis, which Schumann referred 

 doubtfully to C. napoleonis. 



In the New York Botanical Garden herb- 

 arium are specimens of a Hylocereus collected 

 on Martinique in 1884 by Pere Duss (No. 

 904) , which have the horny-margined ribs and 

 large white flowers of this species. From this 

 island Jacquin in 1763 described a variety 

 aphyllus of Cactus triangularis from the moun- 

 tain forests, which may very likely be this 

 species, in which case Martinique may be the 

 home of this widely cultivated plant. 



Two forms of this species are common in Yucatan. One is called chacoub ; it has white 

 flowers except that the perianth-segments have purple edges and tips ; the fruit is globular 

 and reddish purple. The other form called zacoub has white flowers and oblong and 

 creamy-white fruit ; these fruits are considered among the most desirable in Yucatan and are 

 often to be found in the markets for sale. 



Illustrations: Safford, Ann. Rep. Smiths. Inst. 1908: pi. 6, f. i, as Hylocereus trico- 

 status; Martius, Fl. Bras. 4 2 :pl. 42; Engler and Prantl, Pflanzenfam. 3 fa :f. 57, A, B; 



