Denmoza gen nov

Plant cylindric, often elongated, the numerous, parallel straight ribs slightly undulate; spines in clusters at the areoles; flowers arising from the top of the plant, zygomorphic, scarlet, with a slender throat and very narrow limb; tube proper very short, its mouth closed with a mass of white wool; inner surface of the elongated throat covered with stamens; filaments and style long-exserted; ovary and tube bearing numerous scales, their axils filled with silky hairs; fruit globular, dry, splitting down from the top; seeds black, dull, pitted.

Type species: Echinocactus rhodacanthus Salm-Dyck.

The generic name is an anagram of Mendoza, the province in Argentina, where the plant is native. Only one species is known.

The peculiar mass of white wool near the base of the flower-tube on the inside is not known, as far as our observation goes, in any other cactus, except in two species of Lobivia of doubtful relationship, described by Dr. Spegazzini as species of Echinocactus, and in E. spinifiorus, all of which are otherwise quite different from Denmoza.

The genus here segregated was considered by Schumann as a species of Echinopsis but it has also been referred to Cereus, Echinocactus, Cleistocactus, and Pilocereus. In its rather

BRITTON AND ROSE, VOL. III

PLATE VIII

4

M. E. Eaton del. 1. Top of flowering plant of Pediocactus simpsonii.

2. Flower plant of Denmoza rhodacantha.

3. Flowering plant of Ariocarpus kotschoubeyanus.

4. Top of flowering plant of Neoporteria subgibbosa.

(All natural size.)

narrow flowers and exserted stamens there are suggestions of Cleistocactus, but the plant body is very different. It is more like some species of Echinopsis, to which, however, its flowers show little resemblance. It has no close relationship to Cereus or Cephalocereus.

Denmoza differs from all other genera in this subtribe in producing long bristle-like spines from the flowering areoles of very old plants.

1. Denmoza rhodacantha (Salm-Dyck).

Echinocactus rhodacanthus Salm-Dyck, Hort. Dyck. 341. 1834.

Echinopsis rhodacantha Salm-Dyck, Cact. Hort. Dyck. 1849. 39. 1850.

Cleistocactus rhodacanthus Lemaire, Illustr. Hort. 8: Misc. 35. 1861.

Pilocereus erythrocephalus Schumann, Gesamtb. Kakteen 195. 1897.

Cereus erythrocephalus Berger, Rep. Mo. Bot. Gard. 16: 69. 1905.

Pilocereus rhodacanthus Spegazzini, Anal. Mus. Nac. Buenos Aires III. 4: 485. 1905.

Simple, at first globular, often 3 to 6 din. long, but becoming elongated, and when of great age 1.5 meters high and dm. in diameter; ribs 15 to 20 or even 30, broad at base, separated by narrow intervals, about 1 cm. high; young areoles felted, circular, when old 8 to 10 mm. in diameter, usually 1 to 2 cm. apart, but on very old plants approximate, perhaps confluent; spines very different on young and very old plants; spines on small plants 6 to 12 at each areole, white or reddish, subulate, more or less curved, 4 cm. long or less; central spine, if present, solitary; spines on the top of old plants slender and longer, 7 cm. long, often accompanied by a row of 10 or more long brown bristles; flowers slender, 4 to cm. long; ovary and flower-tube hearing small, triangular to lanceolate, appressed, acute scales with long white hairs in their axils; perianth-segments small, apparently connivent; filaments red, exserted for at least 1 cm. beyond the tube; style red, exserted; wool at base of throat matted, 6 to 8 mm. bug; fruit 2 cm. in diameter, nearly smooth in age; seeds oblique, 1.5 mm. in diameter.

Type locality: Not cited at place of publication, but doubtless Mendoza, Argentina.

Distribution: Western mountains of Argentina.

Vaupel (Monatsschr. Kakteenk. 31: 13. 1921) gives an interesting description of the species which flowered in Berlin in 1920 where it is grown as Cereus erythro-cephalus.

Pfeiffer gives Echinocactus coccineus (Enum. Cact. 50. 1837) as a synonym, while Weber gives Cereus rhodacanthus Weber (Dict. Hort. Bois 472. 1896) as a synonym, but neither is described. It is not at all unlikely that Mammillaria coccinea C. Don (Loudon, Hort. Brit. 194. 1830; Cactus coccineus Gillies), said to have come from Chile, is also to be referred here.

Schumann refers here Echinopsis aurata Salm-Dyck and Echinocactus dumesnilianus Cels but these references are very doubtful; they probably belong to Eriosyce ceratistes.

The following varieties have been referred to this species: Echinocactus rhodacanthus coccineus Monville (Labouret, Monogr. Cact. 304. 1853), Echinopsis rhodacantha aurea (Monatsschr. Kakteenk. 17: 76. 1907) and Echinopsis rhodacantha gracilior Labouret (Monogr. Cact. 304.

Illustrations: Blühende Kakteen 1: pl. 16; Monatsschr. Kakteenk. 4: 187. f. 3; Möllers Deutsche Gärt. Zeit. 25: 481. f. 12, as Echinopsis rhodacantha.

Plate viii, figure 2, shows a flower of a plant brought by Dr. Rose to the New York Botanical Garden in 1913, which bloomed in 1917. Figure 93 is from a photograph taken by Paul G. Russell at Mendoza, Argentina, in 1915.

Fig. 93.—Denmoza rhodacantha.

2. ARIOCARPUS Scheidweiler, Bull. Acad. Sci. Brux. 5: 491. 1838.

Anhalonium Lemaire, Cact. Gen. Nov. Sp. 1. 1839.

Plants spineless,* usually simple, low, with a flat or round top; tubercles tough, horny, or cartilaginous, triangular, imbricated, spirally arranged, the lower part tapering into a claw, the upper or blade-like part expanded; areoles terminal or at the bottom of a triangular groove near the middle of tubercle, filled with hair when young; flowers appearing from near the center on young tubercles, diurnal, rotate-campanulate, white to purple; fruit oblong, smooth; seeds black, tuberculately roughened, with a large basal hilum; embryo described as obovate, straight.

Type species: Ariocarpus retusus Scheidweiler.

This genus long passed under the name of Anhalonium, but it was found that Ariocarpus had priority and hence was taken up. Karwinsky proposed the name Stromatocactus for one of the species, but no description of it was ever published. The genus is usually considered as most closely related to Mammillaria, under which genus two of the species have been placed. Engelmann, who was greatly puzzled over the group, first considered it the same as Mammillaria, then as a subgenus of Mammillaria, and later as a distinct genus.

In its small, oblong, naked fruit and straight embryo, it suggests a Mammillaria, but in its tubercles, areoles, seeds, and absence of spines, it is very unlike any of the species of that genus.

The generic name is from the genus Aria and fruit Kappog, referring to the Aria-like fruit. We recognize three species, natives of southern Texas and northern Mexico.

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