2IO THE CACTACEAE. 



Lemaire in 1839 listed the species and also described the variety major Lemaire (Cact. 

 Gen. Nov. Sp. 80. 1839), which he stated to be three times as stout as the species. To 

 the variety he referred C. rigidus Lemaire, but this he seems never to have described. 



In 19 13 Weingart sent Dr. Rose a cutting labeled Cereus rigidus which is still growing 

 in the Cactus House of the U. S. Department of Agriculture but it has never flowered. It 

 gives off aerial roots and otherwise looks like a Selenicereus but is clearly distinct from any 

 of our described species. The stem is slender, about 8 mm. in diameter, strongly 5-angled; 

 areoles closely set, about 8 mm. apart; spines small, acicular, the centrals a little stouter 

 than the radials, bulbose at base and yellowish brown in color. Weingart's plant proves 

 to be the same as No. 6791 received from M. Simon of St. Ouen, Paris, under the name 

 Cereus pentagonus, at the New York Botanical Garden. 



Salm-Dyck in 1845 listed the varieties rigidior and myriacaulon* The latter name he 

 published in 1850 (Cact. Hort. Dyck. 1849. 22, 222), when he states that the species has 

 short spreading branches about 7.5 cm. long, while the variety is even shorter, slenderer, 

 and often appressed to the ground. He would refer here Cereus pentalophus radicans De 

 Candolle (Mem. Mus. Hist. Nat. Paris 17: 117. 1828). 



Several of the West Indian species of Selenicereus are known to us to develop very little 

 for long periods after commencing growth; we suspect that the name Cereus humilis was 

 based on a plant in that condition. 



Cereus maynardii Paxton, Bot. Mag. 14: 75. 1847. 



Cereus grandiflorus speciosissimus Pfeiffer, Enum. Cact. 113. 1S37. 

 Cereus grandiflorus hybridus Haagein Forster, Handb. Cact. 415. 1846. 

 Cereus grandiflorus maynardii Pa.xton, Rev. Hort. III. 1: 285. 1847. 

 Cereus fulgidus] Hooker in Curtis's Bot. Mag. 96: pi. 5856. 1870. 

 Cereus grandiflorus ruber Riimpler in Forster, Handb. Cact. ed. 2. 751. 1885. 



Stems bright green, 3 or 4-angled, 3.5 cm. in diameter; spines about 9 in each cluster, acicular, 

 12 to 18 mm. long, straw-colored, with brown tips; flowers 15 to 18 cm. broad; flower- tube 7.5 

 to 10 cm. long, bearing small red scales with hairs in their axils; flower parts in several series, 

 scarlet ; stamens numerous, shorter than the inner perianth-segments ; style elongate ; stigma-lobes 

 numerous, linear, white. 



This is known to be of hybrid origin, being a cross between Selenicereus grandiflorus 

 and Heliocereus speciosus. 



The publication of the combination Cereus maynardii has been only incidental and 

 is attributed to both Paxton and Lemaire. As it is named for Viscountess Maynard, it 

 should have been spelled maynardae. 



Illustrations: Paxton's Bot. Mag. 14: pi. opp. 75, as Cereus grandiflorus maynardi; 

 FT Serr. 3 : pi. 233, 234, as Cereus grandifloro-speciosissimus maynardii; Curtis's Bot. Mag. 

 96: pi. 5856, as C. fulgidus; Deutsche Gart. Zeit. 9: 276, as C. hybridus. 



4. MEDIOCACTUS gen. nov. 



A more or less epiphytic cactus, usually growing in trees, with long procumbent branches; 

 branches usually 3-winged, slender, producing aerial roots, the areoles short -spiny; flowers large, 

 funnelform, nocturnal, the tube bearing distant scales; inner perianth-segments white; ovary 

 tuberculate, its felted and spiny areoles subtended by small scales; fruit oblong, red, its areoles 

 felted and spiny. 



In habit and flowers this plant much resembles Hylocereus, but differs from it in its 

 tuberculate ovary and in the felted and spine-bearing areoles of the fruit, which resemble 

 those of Selenicereus. 



The genus has 2 species, so far as known to us, the type being Cereus coccineus Salm- 

 Dyck. Its name implies intermediate characters as it suggests both Hylocereus and 

 Selenicereus. 



* Walpers (Repert. Bot. 2: 278. 1843) gave this variety as a synonym of this species, 

 t Cereus fulgens (Monatsschr. Kakteenk. 6: 190. 1896) is a misspelling. 



