USMAIREOCEREUS. 



99 



Illustrations: Bull. Soc. Acclim. France 52:!'. 4; Cact. Mex. Bound, pi. 74, f. 15; 

 Hornaday, Campfires on Dos. and Lava opp. 68, 136; MacDougal, Bot. X. Amir. I its. 

 pi. S; Monatsschr. Kakteenk. 17: 105, as Cereus thurberi. 



Figure 143 is from a photograph taken by Dr. MacDougal at Torres, Sonora, in 1902; 

 figure 144a shows a flower of the plant collected by F. E. Lloyd on the Quijotoa Moun- 

 tains, Arizona, in 1906; and figure 1446 shows a fruit of the same. 



18. Lemaireocereus laetus (IIBK.) Britton and Rose, Journ. X. V. Bot. Card. 20: 157. n;n,. 



Cactus laetus Humboldt, Bonpland, and Kunth, Nov. Gen. et Sp. 6: 68. 1823. 

 Cereus lad us Dc Candolle, Prodr. 3: 466. 1828. 



Plant 4 to 6 meters high, much branched, bluish gray but not glaucous; ribs 4 to 8, prominent ; 

 areoles 2 to 3 cm. apart ; spines brown when young, becoming gray to nearly white in age, usually 

 1 to 3 cm. but sometimes 8 cm. long, subulate; flowers 7 to 8 cm. long; inner perianth-segments 

 white, 2 em. long; fruit green without, very spiny, splitting down the side when ripe, white within; 

 pulp edible; seeds black. 



Type locality: Near Sondorillo, formerly in Ecuador but now in Peru. 



Distribution: Central Peru and southern Ecuador. 



Dr. Rose found the species in Catamayo Valley in southern Ecuador, where it is very 

 common (No. 23340) ; it was, however, seen only in this one locality in Ecuador. We also 

 refer here the plant collected by Dr. and Mrs. Rose along the Rimac River below Matucana, 

 Peru, July 9, 1914 (No. 18650). 



Fig. 145. — Lemaireocereus laetus. 



Fig. 146. — Lemaireocereus laetus 



We have referred here the plant from Catamayo, as it is the only wild one we know 

 in this region which could possibly have been described as Cactus laetus. It is such a con- 

 spicuous plant that we do not believe Humboldt would have passed it by without some 

 reference. Through the kindness of Dr. Charles Wood we were able to send to the 

 Natural History Museum of Paris specimens of this Catamayo plant in order to have it 

 compared, if possible, with Humboldt's type. M. Lecomte, however, informs us that no 

 specimen can be found. It is of interest to note that in 1825 Sprengel, who redescribed 

 this species in his edition of the Systema, placed it next to Cereus churn cus and questions 

 whether it is not the same as C. hystrix. 



The original description of Cactus laetus is very brief and unsatisfactory. 



