I'ACHYCIvRF.rS. 



73 



by dense masses of brownish wool; areoles approximate or even confluent; radial spines aboul i _\ 

 slender; centrals 3, 1 very long, sometimes u to [3 cm. long; Bowers borne mar the tups of the stems 

 or branches, 6 to 7 cm. long; the bud, afterwards the flower, and finally the fruit, completely con- 

 cealed in the long wool; ovary covered with small, pale, imbricated scales; Bower-tube also covered 

 with imbricated scales, but these larger and pinkish, pointed; Bowers doubtless opening at night, but 

 still expanded at 8 o'clock in the morning; tube proper 10 mm. long or less; throat funnelform, 3 cm. 

 long; inner perianth-segments numerous, 1.5 to 3 cm. long, eream-colored; inner perianth segments 

 and stamens inflexed after anthesis, with the stiff outer perianth-segments pressed down upon them : 

 stamens attached all over the throat, the innermost and lower row united at base and appressed 

 against the style; filaments cream-colored; style stout, stiff, 7.5 cm. long, cream-colored; stigma- 

 lobes linear, erect, cream-colored. 



Fig. 107. — Pachycereus chrysomallus. 



Type locality: Mexico. 



Distribution: Puebla and Oaxaca, Mexico. 



This is one of the characteristic plants on the mesas around Tehuacan. When fully 

 grown, it is a very large plant with many upright branches ; the trunk and old branches are 

 stout and woody, making it very difficult to obtain botanical specimens. In 1906 Dr. 

 MacDougal and Dr. Rose shipped a very large plant to the New York Botanical Garden, 

 which flowers annually and from which an abundance of flowers has been obtained. 



Cereus militaris Audot (Rev. Hort. II. 4:307. 1845) and Pilocereus militaris (Salm- 

 Dyck, Cact. Hort. Dyck. 1849. 40. 1850, as synonym) probably belong here. 



Illustrations: Contr. U. S. Nat. Herb. 10: pi. 18; MacDougal, Bot. N. Amer. Des. pi. 

 16; Xat. Geogr. Mag. 21: 699, as Pilocereus fulviceps; Contr. U. S. Nat. Herb. 12: pi. 66. 



Plate xi illustrates the top of a flowering plant in the New York Botanical Garden 

 brought from Tehuacan, Mexico, by Dr. MacDougal and Dr. Rose in 1906. Figure 107 is 

 from a photograph taken by Dr. Rose near Tehuacan, in 1906; figure 108 shows the flower 

 of this plant; and figure 109 a longitudinal section of the flower. 



