n8 



THE CACTACEAE. 



Key to Species. 



Flower-tube longer than the limb i. N. serpentina* 



Flower-tube not longer than the limb. 

 Flowers 4 to 7 cm. long. 



Spines acicular; ribs acute 2. TV. hirschtianus 



Spines subulate; ribs obtuse 3- N. guatemalensis 



Flowers 9 cm. long or more. 



Perianth-segments long-aeuminate 4. N. neumannii 



Perianth-segments acute or obtusish 5- N. oaxacensis 



1. Nyctocereus serpentinus (Lagasca and Rodrigues) Britton and Rose, Contr. U. S. Nat. Herb. 12: 

 423. 1909. 



Cactus serpentinus Lagasca and Rodrigues, Anal. Cienc. Nat. Madrid 4: 261. 1801. 



Cactus ambiguus Bonpland, Descr. PI. Rares 90. 1813. 



Cereus serpentimis De Candolle, Prodr. 3: 467. 1828. 



Cereus ambiguus De Candolle, Prodr. 3: 467. 1828. 



Cereus serpentinus stellatus Lemaire, Cact. Gen. Nov. Sp. 78. 1839. 



Cereus serpentinus splendens Salm-Dyck in Lemaire, Cact. Gen. Nov. Sp. 79- 1839. 



Cereus splendens* Salm-Dyck, Cact. Hort. Dyck. 1849. 214. 1850. 



Echinocereus serpentinus Lemaire, Cact. 57. 1868. 



Echinocereus splendens Lemaire, Cact. 57. 1868. 



Cereus serpentinus albispinus\ Weingart, Monatsschr. Kakteenk. 18: 30. 1908. 



Stems growing in a cluster or clump, at first erect, then clambering through bushes or over 

 walls or, when without support, creeping or hanging, often 3 meters long, 2 to 5 cm. in diameter; 

 ribs 10 to 13, low and rounded; areoles close together, felted and with acicular or bristle-like spines; 

 spines about 12, white to brownish, the tips usually darker, the longest about 3 cm. long; flowers 

 borne at the upper areoles, sometimes terminal, 15 to 19 cm. long, the limb 8 cm. broad; areoles 

 on ovary and flower-tube bristly ; inner perianth-segments white, spatulate, obtuse ; fruit red, covered 

 with deciduous spines, 4 cm. long; seeds black, 5 mm. long. 



Type locality: Not cited; described from a garden plant. 



Distribution: Mexico, probably native near the eastern coast. 



Cereus serpentinus strictior Walpers (Repert. Bot. 2 : 278. 1843) is only a published name. 



Cereus ambiguus strictior (Weingart, Monatsschr. Kakteenk. 19: 9. 1909) seems never 

 to have been published. 



Cereus kalbreyerianus Werckle (Monats- 

 schr. Kakteenk. 17:38. 1907) is known only 

 from its flowers, which, from the description, 

 closely resemble those of N. serpentinus and it 

 is said to resemble this species in its habit. 

 It was found near Bogota, Colombia. 



Although Mexico is given as the home 

 of this species, no wild specimens have been 

 collected there in recent times; it is now 

 widely cultivated in that country, or is half- 

 wild in hedges or running over walls about 

 yards. A. Berger (Rep. Mo. Bot. Gard. 

 16: 75, 76, 1905) has this interesting note: 



"Cereus serpentinus P. DC. possesses the largest seeds of Cereus known to me. There are only 

 a few in each fruit, bedded in the crystalline red pulp. Several varieties of this species occur in 

 gardens. There are two very pronounced forms at La Mortola. One has weaker and more serpen- 

 tine stems, with smaller spines and smaller flowers. This never produces any fruit. The other form 

 has stronger, upright stems with longer spines. Its flowers are remarkably larger and produce a 

 great quantity of fruits. The former variety seems to have undeveloped stigmata, and it may 

 prove to be the male plant. Similar cases of heterogamy are known in Opuntia and Mammillaria, 

 but nothing of the kind has ever been shown in Cereus. This male form at La Mortola corresponds 

 well with the figure in the Botanical Magazine, pi. 3566. Strictly terminal flowers, as shown in this 

 plate, are also occasionally produced by our plant." 



*We have followed Weingart (Monatsschr. Kakteenk. 18: 30. 1908) in referring this name here rather than to 

 Monvillea cavendishii. 



f Weingart states that this and Cereus albispinus are identical with Cereus splendens. 



Fig. 176. — Fruit of Nycto- 

 cereus serpentinus. X0.7. 



Fig. 177. — Flower of Nycto- 

 cereus hirschtianus. X0.7. 



