Rhipsalis

Some people are surprised that cacti grow in humid tropical rain forests and seasonal forests rather than deserts. Yet in many regions of South America, and in the Old World as well, cacti make up an important component of the epiphytic flora. Rhipsalis is the only cactus that successfully migrated into the Old World without the aid of humans. Fruits of the tribe Rhipsalideae are juicy berries, each containing 10-100 tiny black seeds that possess a gelatinous sticky appendix in the hilum-micropylar region (Barthlott 1983). This is clearly an adaptation for dispersal by birds, which is almost certainly how Rhipsalis was introduced into the Old World. One species, R. baccifera, is now widely distributed in humid tropical Africa, east as far as Sri Lanka. It has not reached the Indian subcontinent. The dispersal occurred long ago, for the Old World populations have become polyploid and are distinct subspecies (Barthlott and Taylor 1995).

612 Rhipsalis

Rhipsalis (type, R. cassutha = R. baccifera) is one of the earliest cactus genera described, by Joseph Gaertner in 1788. The name is derived from the Greek rhips, wickerwork, referring to the slender, flexible stem segments of most of the species. Wilhelm Barthlott and Nigel Taylor (1995) recognized 35 species of Rhipsalis; the International Cactaceae Sys-tematics Group has adopted their classification.

The species of Rhipsalis are characterized as pendulous epiphytes, occasionally lithophytes, usually with spineless stem segments that are round in cross section, and branching almost always acrotonically, that is, at or near the tips of existing stems. The small flowers are rotate and white, the berrylike fruits naked. Plants flower during the day in spring and summer.

Rhipsalis Gaertner 1788, conserved name Erythrorhipsalis A. Berger 1920

Subfamily Cactoideae, tribe Rhipsalideae. Plants epiphytic, rarely lithophytic, usually pendulous shrubs. Stem segments cylindrical, usually round in cross section but occasionally angled, ribbed, winged, or flat, more orless spineless; new segmentsarisingsinglyorinclustersat or near the tips of older segments, growth determinate or indeterminate. Areoles small; terminal areolessometimes absent. Spines usually absent. Flowers small, rotate, usually white; pericarpels round in cross section, usually naked but sometimes with soft bristles; floral tubes very short or absent; disk sometimes present, annular, producing nectar. Fruits small, berrylike, naked. Distribution: primarily eastern Brazil but throughout tropical America, the Caribbean (from where the first collection probably was made), and one species also in tropical Africa, Madagascar, and on islandsofthe Indian Ocean asfareastasSri Lanka.

Barthlott and Taylor (1995) recognized five subgenera: Calamor-phipsaiis, Epallagogonium, Erythrorhipsalis, Phyilarthrorhipsalis, and Rhipsalis.

Rhipsalis baccifera (J. S. Miller) Stearn 1939 Cassytha baccifera J. S. Miller 1771, as "Cassyta" Cactus pendulus Swartz 1788, Rhipsalis pendula (Swartz) Link & Otto 1827

Rhipsalis cassutha Gaertner 1788

Cactus fasciculatus Willdenow 1813, Rhipsalis fasciculata (Willdenow) Haworth 1819, R. baccifera subsp. fasciculata (Willdenow) Siipplie 1996

Rhipsalis cassutha [var.] mauritiana A. P. de Candolle 1828, R. baccifera subsp. mauritiana (A. P. de Candolle) Barthlott 1987 Rhipsalis cassythoides G. Don 1834 Rhipsalis dichotoma G. Don 1834 Rhipsalis hookeriana G. Don 1834 Rhipsalis undulata Pfeiffer 1837 Rhipsalis aethiopica Welwitsch 1859

Rhipsalis horrida Baker 1884, Hariota horrida (Baker) Kuntze 1891, R. baccifera subsp. horrida (Baker) Barthlott 1987

Rhipsalis madagascariensis F. A. C. Weber 1889

Rhipsalis minutiflora K. Schumann 1890

Rhipsalis pilosa F. A. C. Weber ex K. Schumann 1890

Rhipsalis comorensis F. A. C. Weber 1891

Rhipsalis suareziana F. A. C. Weber 1892

Rhipsalis zanzibarica F. A. C. Weber 1893

Rhipsalis erythrocarpa K. Schumann 1895, R. baccifera subsp.ery-

throcarpa (K. Schumann) Barthlott 1987 Rhipsalis caripensis F. A. C. Weber ex K. Schumann 1898 Rhipsalis cassutha\iar. rhodocarpa F. A. C. Weber 1898, R. baccifera subsp. rhodocarpa (F. A. C. Weber) Supplie 1990 Rhipsalis suarensis F. A. C. Weber 1898 Rhipsalis cassythoides Loefgren 1918 Rhipsalis guineensis A. Chevalier 1920 Rhipsalis shaferi Britton & Rose 1923, R. baccifera subsp.shaferi

(Britton & Rose) Barthlott & N. P.Taylor 1995 Rhipsalis bartlettii Clover 1938 Rhipsalis heptagona Rauh & Backeberg 1957 Rhipsalis cassuthopsis Backeberg 1959 Rhipsalis coralloides Rauh 1962, not validly published Rhipsalis quellebambensis H. Johnson ex Backeberg 1966, not validly published Rhipsalis hylaea F. Ritter 1981

Rhipsalis cereoides 61 3

Rhipsalis baccifera subsp. hileiabaiana N. P. Taylor & Barthlott 1995 Rhipsalis baccifera subsp. fortdauphiriensis Supplie 1996

Plants epiphytic or lithophytic, pendent, 1-4 m (3.3-13 ft) long, extension shoots of indeterminate growth, with composite areoles, branching acrotonic. Stems long, cylindrical, slender, not dimorphic, 4-6 mm (0.2 in) in diameter. Areoles sometimes with one or two stiff bristles to 1 mm long. Flowers borne laterally in winter or spring, whitish, 5-10 mm (0.2-0.4 in) in diameter. Fruits spherical, translucent, white or pinkish, 5-8 mm (0.2-0.3 in) in diameter. Distribution: tropical America, tropical Africa, Madagascar, Seychelles, Mauritius, Réunion, and Sri Lanka.

Six subspecies are recognized in Rhipsalis baccifera, the most widespread of all cactus species. Subspecies baccifera is mostly an epiphyte but at times a lithophyte; it is found in the Neotropics, including the Caribbean, eastern Mexico, Florida, Central America, and northern South America, and both diploid and tetraploid populations have been found. Subspecies erythrocarpa is tetraploid but its range is limited to mountains of east Africa. Subspecies hileiabaiana is very densely branched and is found in Bahia, Brazil. Subspecies horrida is an interesting neotenic form that is both epiphytic and lithophytic and has an aberrant branching pattern; it has tetraploid and octoploid populations and occurs only in Madagascar. Subspecies mauritiana is the widespread tetraploid subspecies that occurs in the Old World, from tropical Africa east to Sri Lanka. Subspecies shaferi usually has shorter, stiffer stem segments than subspecies baccifera and is found in Paraguay, southern Bolivia, and northern Argentina.

Rhipsalis hurchellii Britton & Rose 1923 Erythrorhipsalis burchellii (Britton & Rose) Volgin 1981

Plants epiphytic, with many weak, pendent branches in whorls, or forking, growth determinate, with composite areoles. Stem segments long, round in cross section, very slender and hardly succulent, dichotomous; primary branches to 60 cm (24 in) long, terminal branches to 6 cm (2.4 in) long and 1-2 mm in diameter, light green to purplish. Areoles with wool, bristles absent. Flowers borne at the stem tips, bell shaped, often numerous, whitish, to 15 mm (0.6 in) long. Fruits brilliant reddish magenta to purplish magenta. Distribution: seasonal Atlantic forest in southeastern and southern Brazil.

Rhipsalis campos-portoana Loefgren 1918 Erythrorhipsalis campos-portoana (Loefgren) Volgin 1981

Plants epiphytic, with pendent or arching branches, growth determinate, with composite areoles. Stem segments slen der, round in cross section, cylindrical, dichotomous; primary stems elongated, terminal branches usually in wholes of three or four, club shaped, 3-5 cm (1.2-2 in) long, 1-2 mm in diameter, light green. Areoles naked. Flowers borne apically, whitish, not opening widely, to 9 mm (0.4 in) long. Fruits globose, orange. Distribution: Atlantic and cloud forests of southeastern and southern Brazil.

Rhipsalis cereoides (Backeberg &Voll) Backeberg 1937-1938 Lepismium cereoides Backeberg &Voll 1935

Plants lithophytic, bushy, pendent or semierect, growth indeterminate. Stem segments three-angled, rarely four-angled, not scalloped, dull bluish green, 4-10 cm (1.6-3.9 in) long, 1-7 cm (0.4-2.8 in) in diameter. Areoles small, not sunken, often with two to four short bristles. Flowers borne singly or in clusters of two to four in spring, disk shaped, white, to 2 cm (0.8 in) in diameter. Fruits pale pink. Distribution: gneissic inselbergs in eastern Brazil.

614 Rhipsalis cereuscula

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