5 2 THE CACTACEAE. 



36. Cephalocereus robustus nom. nov. 



Pilocen-ns nli-i Schumann, Gesamtb. Kaktccn Nachtr. 64. 1903. Not Cephalocereus ii/ei Giirke, 1908. 

 Cereus n/i'i IVr.m-t, Krp. Mo. Bot. Card. 16: 70. 1905. 



Tall, much branched, with a rather indefinite trunk, 3 to 7 meters high, pale whitish blue, 

 rotighish; ribs 8 or 9, high, separated by acute intervals; areoles closely set, with short dark spines 

 ami longer silky hairs; 3 of the ribs bearing flowers and their flowering areoles producing long, curly, 

 white hairs, 5 to 6 cm. long; flower nocturnal, 5 cm. long, its tube proper i cm. long; perianth- 

 segments acute, nearly white; stamens numerous, scattered all over the broad long throat, scarcely 

 exserted; anthers purple; style slender, included; fruit 2 cm. in diameter; seeds minute, black, 

 shining. 



TV pc locality: Cabo Frio, Rio de Janeiro, Brazil. 



Distribution: Coast of State of Rio de Janeiro, Brazil. 



This species is common on the hills about Araruama Lake and near Cabo Frio, where 

 it forms small forests and is the dominant feature of many landscapes. Dr. Rose and 

 Senor Campos Porto obtained from Sao Pedro, near Cabo Frio, a living specimen (No. 

 20706) which flowered in the New York Botanical Garden in July 1916. 



This plant is very unlike any of the other Brazilian species of this genus, of which 

 there are at least three in the State of Rio de Janeiro. 



Figure 75 is from a photograph of a specimen collected by Dr. Rose near Sao Pedro, 

 Rio de Janeiro, in 1915. 



37. Cephalocereus cometes (Scheidweiler) Britton and Rose, Contr. U. S. Nat. Herb. 12 : 416. 1909. 



Cereus cometes Scheidweiler, Allg. Gartenz. 8: 339. 1840. 

 Pilocereus jubatus Salm-Dyck in Forster, Handb. Cact. 356. 1846. 

 Cereus flaricomus Salm-Dyck, Cact. Hort. Dyck. 1849. 202. 1850. 

 Pilocereus flavicomus Riimpler in Forster, Handb. Cact. ed. 2. 658. 1885. 



Erect, cylindric; ribs 12 to 15 (Schumann says 9 to 12), hardly tuberculate, obtuse; areoles close 

 together, round; spines unequal, straight, spreading, 2 cm. long or less, flesh-colored or brownish, 

 becoming gray ; flowering areoles bearing masses of yellow hairs or wool, longer than the spines; 

 neither the flowers nor the fruit known. 



Type locality: Near San Luis Potosi, Mexico. 



Distribution: State of San Luis Potosi, Mexico. 



A small specimen in the New York Botanical Garden (No. 6710) has 12 ribs, with are- 

 oles bearing long white deciduous hairs and short spines, brownish at first, becoming gray. 



Forster (Handb. Cact. 357. 1846) gave both Pilocereus cometes Mittler and Cereus 

 jubatus Salm-Dyck, as synonyms of P. jubatus. See also Schelle, Handb. Kakteenk. 104. 1907. 



Figure 76 is from a photograph of a plant in the collection of the New York Botanical 

 Garden obtained from M. Simon of St. Ouen, Paris, France. 



38. Cephalocereus leucocephalus (Poselger) Britton and Rose, Contr. U. S. Nat. Herb. 12:417. 1909. 



Pilocereus leiicoceplialns Poselger, Allg. Gartenz. 21: 126. 1853. 

 1'ilivcreus houlletii Lemaire, Rev. Hort. 1862: 428. 1862. 

 Pilocereus foersteri Lemaire, Illustr. Hort. 13: under pi. 472. 1866. 

 Cereus houlletii Berger, Rep. Mo. Bot. Gard. 16: 70. 1905. 



Plants 2 to 5 meters high, branched below, the branches 3 to 15, erect or ascending; ribs usually 

 12, low; spines about 10 in each cluster, acicular, 12 to 20 mm. long; flowering areoles clustered on 

 one side of the plant toward the top and producing an abundance of long white hairs (sometimes 4 

 to 10 cm. long); flowers and fruit not seen. 



Type locality: Near Horcasitas, Sonora, Mexico. 



Distribution: Sonora and southeastern Chihuahua, Mexico. 



This species has been much misunderstood in recent years. The specific name houl- 

 letii is a clear synonym of the older name 1cncoccplialus. Both were described as species 

 of Pilocereus and based on plants from Sonora, Mexico, but no further Sonoran material 

 being collected the name was transferred to an East Mexican species from Vera Cruz 



