Pterocactus tuberosus Pfeiffer

Opuntia tuberosa Pfeiffer, Enum. Cact. 146. 1837.

Pterocactus kuntzei Schumann, Monatsschr. Kak-teenk. 7: 6. 1 897.

Pterocactus kurtzei Schumann in Engler and Prantl, Pflanzenfam. Nachtr. 259. 1897.

Pterocactus decipiens Gürke, Monatsschr. Kakteenk. 17: 147. 1907

Roots tuber-like, single or in clusters, usually small but sometimes large and thick, up to 12 cm. long by 8 cm. in diameter, deep-seated, giving off several erect stems, these branching at surface of the ground; terminal branches purplish, turgid, 3 to 40 cm. long, 1 cm. in diameter, more or less clavate; areoles numerous, small, bearing numerous small white appressed spines; flowers terminal, 2 to 3 cm. long; petals long, lanceolate, apiculate, yellow; ovary with numerous areoles bearing long bristles; ovules numerous; fruit dry; seeds large, flat, winged, 10 to 12 mm. in diameter.

Type locality: Near Mendoza, Argentina.

Distribution: Western provinces of Argentina, chiefly in the mountains.

We have not seen the type of P. kuntzei, which is doubtless at Berlin, but we have examined cotypes in the Kurtz Herbarium at Córdoba, Argentina, and at New York.

Opuntia tuberosa, described from Mendoza as long ago as 1837, has long been a puzzle to botanists, who have tried to associate it with various opuntias. Dr. Rose, who visited Mendoza in 1915, found a tuberous-rooted cactus in the mountains above that city, which we are convinced is the plant described by Pfeiffer. There is no doubt, on the other

Fig. 37—Pterocactus tuberosus. Natural size. Photograph by Paul G. Russell.

hand, that it is Pterocactus kuntzei, from the same region, which was described as new by Schumann in 1897.

Opuntia alpina Gillies (Pfeiffer, Enum. Cact. 146. 1837) was not published, but was given as a synonym of Opuntia tuberosa. Schumann referred both names to Opuntia platyacantha.

Illustrations: Monatsschr. Kakteenk. 7: 7; Schumann, Gesamtb. Kakteen f. 107, both as Pterocactus kuntzei; Blühende Kakteen 3: pl. 140, as P. decipiens.

Figure 36 shows a seed of a plant, collected by Dr. Rose near Mendoza, Argentina, in 1915; figure 37 is from a photograph of same plant; figure 38 is from a photograph taken by Dr. Carlos Spegazzini.

Fig. 38.—Pterocactus tuberosus

3. NOPALEA Salm-Dyck, Cact. Hort. Dyck. 1849. 63. 1850.

Much branched cacti with definite cylindric trunks; roots so far as known fibrous; branches or joints flattened, fleshy, often narrow; glochids usually less abundant than in Opuntia; spines solitary or in clusters at the areoles, sheathless; leaves small, subterete, soon deciduous; areoles bearing white wool, glochids, and often spines; flowers originating in the areoles usually at or near the edges of the joints; sepals ovate, erect; petals red or pinkish, erect, closely appressed against the numerous stamens and the style; filaments and style slender, much longer than the petals; ovary more or less tuberculate, naked or spiny, with a very deep umbilicus; fruit a juicy berry, red, edible, usually spineless; seeds numerous, fiat, covered by a hard bony aril.

Nopalea is closely related to Opuntia, with which it is sometimes united; the erect petals and elongated filaments and style are constant in Nopalea, however.

Three species were included by Salm-Dyck in this genus when it was described, of which Opuntia cochenillifera Linnaeus was the first and is therefore considered the type.

Karl Schumann described five species in his monograph, but since then two species, N. guatemalensis and N. lutea, have been described by Dr. Rose, and one, N. inaperta, by Dr. Griffiths. N. moniliformis (Linnaeus) Schumann, based on plate 198 of Plumier, is Opuntia moniliformis (Linnaeus) Steudel.

The species are natives of Mexico and Guatemala, and have been accredited to Cuba, although none has recently been observed wild on that island. Some of them are widely cultivated and may be found throughout the warmer parts of the world. Two are of some economic importance and two or three are grown as ornamentals.

The name Nopalea is doubtless from nopal, the common name of Mexicans for certain opuntias and nopaleas.

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