Columnar plants with numerous low ribs and when flowering developing a pseudocephalium similar to that of some species of Cephalocereus; areoles strongly armed with spines, and bearing long white hairs; flowers small, short-campanulate, nearly hidden by the surrounding wool, probably opening at night; tube short; outer penauth-segments pinkish, the inner ones probably white; stamens and style short, included; scales on ovary and flower-tube small, acute, with long silky caducous hairs; fruit subglobose to broadly obovoid, smooth, its flesh pure white, slightly acid, very juicy, edible; seeds very small, black, shining.

This genus resembles the typical species of Cephalocereus. Berger suggested that it was an Oreocereus, but this was before he had seen any flowers of the latter; we now know that there is much difference not only in the flowers but also in the fruit and seeds. It is named for Nicolas E. Esposto, a very keen botanist who is connected with the Escuela Nacional de Agricultura at Lima, Peru.

1. Espostoa lanata (HPK.).

Cactus lanatus Humboldt, Bonpiand, and Kunth, Nov. Gen. et. Sp. 6: 68. 1823.
Cerens lanatus De Candolle, Prodr. 3:464. 1828.
Pilocereus dautwitzii Hauge, Gard. Chron. 1873: 7. 1873.
Pilocereus heagei Rümpler in Förster, Handb. Cact. ed. 2, 665. 1885.
Pilocereus lanatus Weber, Diet. Hort. Bois 965. 1898.
Cereus dautwitzii Orcutt, West Amer. Sci. 13: 63. 1902.
Cleistocactus lanatus Weber in Gosselin, Bull. Mens. Soc. Nice 44:37. 1904.
Pilocereas lanoatus haagei Jostmann, Monatsschr. Kakteenk. 21: 25. 1911.
Oreocereus lanatus Britton and Rose, Stand. Cycl. Hort. Bailey 4: 2404. 1916.

Plant simple, 2 to 4 meters high, sometimes with several strict branches or with a simple erect stem, 4 to 10 cm. in diameter, with many spreading branches at first nearly horizontal or curved upward and becoming erect near the tip, the tip hidden under a mass of hairs and brown bristles; ribs numerous, 20 to 25, low, 5 to 8 mm. high, rounded; areoles rather large, 5 to 6 mm. apart; radial spines numerous, acicular, 4 to 7 mm. long, brownish, intermixed with long white hairs; central spine solitary, yellow or brown to black, subulate, 2 to 5 cm. long; flowers borne on one side of the stem from a prominent pseudocephalium, 3.5 to 5 cm. long; scales on the tube many, triangular lanceolate, acute, about 6 cm. long; fruit 3 to 4 cm. long, juicy, edible, white except the small pinkish scales; seeds 1 mm. broad.

Type locality: Near Rio Aranza and Guancabamba, Ecuador.
Distrihution: On the dry hills of northern Peru and Ecuador, altitude 1,200 to 2,250 meters.

Figs 87. and 88. - Espostoa lanata

In 1918, while in Ecuador, Dr. Rose attempted to reach the exact locality of Humboldt's Cactus Ianatus, but was unsuccessful. In the Catamayo Valley somewhat north of Humboldt's station and in what is doubtless a part of the same desert he collected this species and upon this our description above is largely based. These plants are so different in habit from other plants collected by Dr. Rose in central Peru that we have been very much in doubt whether they should all be referred here or a part separated as a new species. That there is more than one species in this genus has been further suggested since receiving a photograph from G.M. Dyott, taken at Chagual, on the west bank of the Marañon River, in northern Peru. In this photograph are shown several very striking cactus plants, perhaps of this genus, but very unlike any we have heretofore seen.

Fig 89. - Flower of Espostoa lanata. Fig.90. - Fruit of same

We have followed most recent writers in combining Cereus dautwitzii with Cereus lanatus, although we have not seen the type of either. We know, however, that Cereus dautwitzii came from Huancabamba, Peru, while Cactus lanatus, upon which Cereus lanatus was based, came from Guancabamba, Ecuador; the names, varying only in the initial letter, are different spellings for the same place. The northern boundary-line of Peru has pushed north since Humboldt visited this region; his station of Guancabamba is now in Peru instead of Ecuador.

The sweet, edible fruit is called soroco in southern Ecuador; it is also called piscol colorado, according to Humboldt.

Fig 91. - Espostoa lanata

The typical form was collected by J. N. Rose, A. Pachano, and George Rose in the Catamayo Valley, southern Ecuador, October 3, 1918 (No.23326) and the other form was collected by Dr. and Mrs. Rose near Matucana, central Peru, altitude about 7,000 feet, July 9, 1914 (No.18649). Dr. Rose also collected a living plant above Chosica (No.18537) and herbarium specimens between Matucana and San Bartelome (No.18748). Dr. W. H. Osgood has sent us photographs of a cactus which we would refer here. One was taken near Chilete, Peru, altitude 1,000 feet, and the other between Menocucho and Otuzco, Peru, altitude 3,000 feet.

Pilocereus haageanus (Monatsschr. Kakteenk. 6: 96. 1896) is sometimes referred to but was never published.

Illustrations: Dict. Gard. Nicholson 3: f. 152; Fl. Serr. 2I: p1. 2163; Förster, Handb. Cact. ed. 2. f. 87; Gard. Chron. 1873: f. 1; Knippel, Kakteen p1. 29, all as Pilocereus dautwitzii: Cact. Journ. 2: 4, as Pilocereus dautwitzii cristatus, Monatsschr. Kakteenk. 21: 23; 24: 131, both as Pilocereus lanatus; Monatsschr. Kakteenk. 19: 183, as Pilocereus lanatus cristatus: Monatsschr. Kakteenk. 21: 23; 23: 125, both as Piloccreus lanatus haagei.

Figure 87 is from a photograph taken by George Rose in southern Ecuador in 1918; figure 88 is from a photograph taken by Dr. Rose at Matucana, Peru, in 1914; figure 89 shows the flower and figure 90 the fruit of the plant photographed by him; figure 91 is from a photograph taken at the New York Botanical Garden of the plant obtained by Dr. Rose at Chosica, Peru, in 1914.

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