i;n THE CACTACKAK. 



Plate xxv, lignrc i, shows the top of a plant received from the Missouri Botanical 

 C.anlen in 1004, which llowered in the New York Botanical Garden, June 23, 1915; figure 

 j shows a (lowering piece of a plant sent to the New York Botanical Garden from Guaymas, 

 Mexico, \>y Dr. Rose in 1910. Figures 241 and 242 show flowers of a plant collected by Dr. 

 MacDougal at Torres, Sonora, in 1902. 



2. Rathbunia kerberi (Schumann) Britton and Rose, Contr. U. S. Nat. Herb. 12: 415. 1909. 



Cereus kcrbcri Schumann, Gcsamtb. Kaktcen 89. 1897. 



kerberi Gosselin, Bull. Metis. Soc. Nice 44: 33. 1904. 



Columnar, somewhat branched, 2 meters high; ribs 4, compressed; radial spines about 16, 

 subulate; central spines 4, stouter than the radials, 4.5 cm. long; flowers 12 cm. long; outer perianth- 

 segments linear-lanceolate, rose-colored, reflexed; stamens exserted; scales on the ovary lanate in 



1 he axils. 



Type locality: On Volcano of Colima, Mexico. 



Distribution: Known only from the type locality. 



Dr. Rose saw flowers of this plant in the herbarium of the Botanical Garden at Berlin 

 in 1912 and noted that it was a Rathbunia; otherwise it is known to us only from descrip- 

 tion. In transferring it to Ratlibitnia (loc. cit.) we associated specimens with it from Sinaloa 

 and Tepic, Mexico, which now appear better referable to Rathbunia alamosensis, although 

 the flowers are longer than in typical specimens (8 to 10 cm. long) and somewhat curved. 



31. ARROJADOA gen. nov. 



Stems low, much branched, cylindric; roots fibrous; ribs numerous, low, straight; areoles clo?e 

 together, bearing small acicular spines; flowers diurnal, borne in a pseudocephalium at the top of 

 stem or branch, small, red or pink, resembling in color and size that of a large Cactus (Mclocaclus), 

 nearly cylindric, the tube short; perianth-segments in several rows, short, erect; stamens and style- 

 included; fruit a small, oblong, naked, juicy berry; seeds small, black. 



This is a peculiar genus, with no very close allies. The original reference of its two 

 species to Ccrcus is not warranted by any taxonomic considerations, for the structure, 

 origin, and shape of the flowers and fruit are quite different. In size and form the flower is 

 similar to Lophocereus, but here the resemblance ends. Its terminal pseudocephalium is 

 most characteristic, for instead of remaining as a permanent crown of the plant it forms a 

 lateral collar for the new joint which is projected through its center. 



The name is in honor of Dr. Miguel Arrojado Lisboa, the present superintendent of 

 Estrada de Ferro Central de Brazil, to whom Brazil is indebted for the extensive botanical 

 exploration of the semiarid regions made a few years ago. 



The genus contains 2 species, of which Ccrcus rhodantlnts is selected as the type. 



KEY TO SPECIES. 



Branches short and thick, 2 to 4 cm. in diameter ............................................... i. .1. rhodantha 



Branches long and slender, i to i .5 cm. in diameter ........................................... 2. A. penicilluta 



1. Arrojadoa rhodantha (Giirke). 



Ccrcus rhodanthus Giirke, Monatsschr. Kakteenk. 18: 69. igoS. 



LOW, i to 2 meters long, at first erect, afterwards branching and clambering; joints short, 

 cylindric, 2 to 4 cm. in diameter; ribs 10 to 13, low; areoles small, approximate, usually less than i 

 em. apart; spines at first brown, in age white, the central ones similar to the radials except a little 

 longer, when young accompanied by some long cobwebby hairs; bristles at the tops of the joints 

 Inni;, brown; flowers solitary at the upper areoles, forming in clusters of 12 to 14 at the tops of 

 branches, pink, riyid, 3 to 4 cm. long; ovary and lower part of tube naked; uppermost scales and 

 perianth-segments similar, obtuse; stamens numerous, included; fruit red, oblong to obovate, about 



2 i-m. Ion-. 



7'v/r lociilily: Caatinga de Sao Raimundo, Piauhy, Brazil. 



