I<BMAIREOCSREUS. 97 



Dr. Rose has collected the species at several localities in central Mexico, including the 



type locality (No. 11133). 



Illustrations: Bull. Soc. Acclim. France 52: 18. f. 2, as Cereus queretaroensis; Ann. 

 Rep. Smiths. Inst. 1908: pi. 6, f. 2. 



Figure 142 shows the spine-bearing stem-areoles of an herbarium specimen collected 

 by Dr. Rose near Oueretaro, Mexico, in 1906. 



Fig. 140. — Cluster of spines of Lemaireocereus weberi. X0.7. 



Fig. 141. — Fruit of same. X0.7. 



Fig. 142. — Part of rib, showing spine-clusters of Lemaireocereus queretaroensis. X0.7. 



16. Lemaireocereus montanus sp. nov. 



Tree-like, 6 to 7 meters high, with a definite smooth trunk 1 meter long or more, with few 

 branches, at first spreading, then nearly erect; ribs few, usually 8, prominent areoles 1 to 1.5 em. 

 apart, large, filled with short brown wool; spines few, 6 or less, pale in color, rather stout, one of them 

 longer, sometimes 3 cm. long; flowers 6 to 7 cm. long, opening during the day; outer perianth-seg- 

 ments purplish ; scales on the ovary ovate, 4 to 6 mm. long, imbricated, acuminate, with erose margins. 



This species was found well up on the side of Alamos Mountain, associated with 

 Lemaireocereus thurbcri, but usually at a higher altitude than that at which that species is 

 generally found. It differs from L. thurbcri in its habit, number of ribs, armament, and 

 flowers. Like L. thurbcri it has brown areoles, which are not found in any of the other 

 species except L. queretaroensis of the table-land region of central Mexico. 



Collected by Rose, Standley, and Russell above Alamos, Mexico, March iS, 1910 

 (No. 13039). 



17. Lemaireocereus thurberi (Engelmann) Britton and Rose, Contr. U. S. Nat. Herb. 12 : 426. 1909. 



Cereus thurbcri Engelmann, Amer. Journ. Sci. II. 17: 234. 1854. 

 Pilocereus thurberi Riimpler in Forster, Handb. Cact. ed. 2. 689. 1885. 

 Cereus thurberi liltoralis K. Brandegee, Zoe 5: 191. 1904. 



Usually without a definite trunk, sending up from the base 5 to 20, or even more, erect or ascend- 

 ing branches 3 to 7 meters high, 15 to 20 cm. in diameter, the basal ones usually simple but occasion- 

 ally with lateral branches, this doubtless being caused by injuries to the growing tips; ribs numerous, 

 12 to 17, rather low but sometimes 2 em. high, rounded, separated by narrow intervals; areoles 10 

 to 15 or rarelv 30 mm. apart, large, sometimes becoming 1 em. in diameter, circular, brown-felted, 

 more or less glandular, the whole areole becoming a wax-like mass; spines numerous, aeicular to 

 subulate, unequal, brownish to black, becoming gray in age, the longest ones sometimes 5 em. 

 long; flowers mostly borne near the top of the stem but sometimes 3 dm. below the top, 6 to 7.5 

 cm. long including the ovary, opening during the day; outer perianth-segments broad, reddish, im- 

 bricated, gradually passing into the scales on the tube; inner perianth-segments light purple with 



