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Taxonomy

Physical Description

Family Rhamnaceae:

Deciduous or evergreen, often thorny trees, shrubs, woody climbers, or lianas, rarely herbs. Leaves simple, petiolate, alternate or opposite, pinnately veined or 3-5-veined, entire to serrate, sometimes much reduced; stipules small, caducous or persistent, sometimes transformed into spines. Flowers yellowish to greenish, rarely brightly colored, small, bisexual or unisexual, rarely polygamous, (4 or) 5-merous, hypogynous to epigynous, in mostly axillary, sessile or pedunculate cymes, or reduced to few in fascicles. Calyx tube patelliform or hemispherical to tubular, sometimes absent, at rim with calyx, corolla, and stamens; sepals 4 or 5, valvate in bud, triangular, erect or ± recurved during anthesis, adaxially often distinctly keeled, alternate with petals. Petals 4 or 5, rarely absent, usually smaller than sepals, concave or hooded, rarely nearly flat, often shortly clawed. Stamens 4 or 5, antepetalous and often ± enclosed by petals; filaments thin, adnate to bases of petals; anthers minute, versatile or not, 2(or 4) -celled, dehiscing by longitudinal slits, usually introrse. Disk intrastaminal, nectariferous, thin to ± fleshy, entire or lobed, glabrous or rarely pubescent, free from ovary or tightly surrounding it, or adnate to calyx tube. Ovary superior to inferior, (1 or) 2-4-loculed, with 1(or 2) ovules per locule; ovules anatropous, basal and erect; styles simple or ± deeply 3-lobed or 3-cleft. Fruit either an indehiscent, rarely explosively dehiscent, sometimes winged, schizocarpic capsule, or a ± fleshy drupe with 1-4 indehiscent, rarely dehiscent, pyrenes (stones) . Seeds with thin, oily albumen, sometimes exalbuminous; embryo large, oily, straight or rarely bent.

About 50 genera and more than 900 species: almost cosmopolitan, mainly in subtropical to tropical areas; 13 genera and 137 species (82 endemic, one introduced) in China.

Former classifications usually placed Rhamnaceae in the Rhamnales, together with Vitaceae and Leeaceae (Suessenguth in Engler & Prantl, Nat. Pflanzenfam., ed. 2, 20d. 1953), or together with Elaeagnaceae (Thorne, Bot. Rev. 58: 225-348. 1992) . Orders such as Celastrales, Urticales, and Euphorbiales have often been considered as closely related groups. Recent analyses of DNA sequences strongly supported including the family in the Rosales, beside the closest relatives Barbeyaceae and Dirachmaceae (see Angiosperm Phylogeny Group II, Bot. J. Linn. Soc. 141: 399-436. 2003) . Suessenguth (loc. cit.) grouped the family into five tribes, mainly characterized by fruit characters. Richardson et al. (Kew Bull. 55: 311-340. 2000; Amer. J. Bot. 87: 1309-1324. 2000) revised this tribal classification on the basis of a phylogenetic analysis using rbcL and trnL-F sequences of the plastid genome. Now 11 tribes are recognized, of which four are represented in the Flora area.

The bark, leaves, and fruit of several species of Rhamnus have been used as laxatives, notably R. cathartica and R. frangula. Diverse Old World species of Rhamnus provide yellow and green dyes as well as drugs. Timber of Alphitonia, Colubrina, Hovenia, and Ziziphus species is used for construction, fine furniture, carving, lathework, and musical instruments. Many Ziziphus species yield edible fruit; among them, Z. jujuba (Chinese jujube) and Z. mauritiana (Indian jujube) are cultivated on a commercial scale. Hovenia dulcis is also grown for its edible, fleshy inflorescence stalks. Species of Hovenia, Paliurus, and Rhamnus are cultivated as ornamentals.^[1]

Genus Hamatocactus:

Plants erect, unbranched or branched in basal portion, not deep-seated in substrate. Roots diffuse. Stems unsegmented, bright deep green, hemispheric when young, becoming spheric or ovoid to cylindric, 3.6-12(-20) × 4.5-12 cm, glabrous; ribs 13, spiraling or vertical, slender, crests sinuate, sharp, not interrupted or undulate, narrow; areoles circular or, on older parts of stem, elliptic to ovate, adaxially elongated into short areolar grooves; areolar glands golden, darker with age, cylindric or peglike; cortex and pith firm, not mucilaginous. Spines 11-20 per areole, not obscuring stems, yellowish, whitish, or reddish brown, acicular (rarely central spine flattened), longest spines 12-38 mm; radial spines 10-19 per areole, straight or slightly curved toward stem, longest spines 11-32 mm; central spines 1 per areole, porrect, hooked, terete (rarely flattened). Flowers diurnal, near stem apex, at adaxial edge of areoles or at axillary ends of short areolar grooves, widely funnelform, 3.7-7 × 4-7 cm; outer tepals finely fringed; inner tepals yellow (to ivory) with red bases, 20-25 × 6-9 mm, margins entire, toothed, or lacerate; ovary scaly, hairless, spineless; stigma lobes 5-11, pale yellow to orangish, 3-7 mm. Fruits indehiscent or eventually dehiscent by vertical slits, bright red, spheric or nearly so, ca. 10 × 8-13 mm, fleshy, with 15 or fewer whitish, broad fringed, naked, spineless scales; floral remnant persistent. Seeds black, obovoid, usually 1-1.4 × 0.8-1 mm, minutely papillate; testa cells weakly convex, nearly flat toward proximal end of seed. x = 11.

Species 1: arid regions, sw United States, Mexico.

Hamatocactus has been submerged in Ferocactus or Thelocactus by various authors and grouped with Glandulicactus by others.^[2]

Similar Species

Members of the genus Hamatocactus:

There are approximately 24 species, subspecies, varieties, forms, and cultivars in this genus: H. uncinatus crassihamatus · H. bicolor · H. crassihamatus · H. hamatacanthus · H. hamatocanthus · H. hamatocanthus var. brevispinus · H. hamatocanthus var. davisii · H. hamatocanthus var. gracilispinus · H. hamatocanthus var. sinuatus · H. setispinus · H. setispinus (Engelm.) Britton & Rose var. cachetianus (Labour.) F.M.Knuth · H. setispinus f. cachetianus · H. setispinus f. flavibaccatus · H. setispinus f. orcuttii · H. setispinus flavibaccatus · H. setispinus var. cachetianus · H. setispinus var. hamatus · H. setispinus var. mierensis · H. setispinus var. orcuttii · H. setispinus var. setaceus · H. sinuatus · H. uncinatus · H. uncinatus var. wrightii · H. wrightii

Bibliography

• Anderson, E. F. (2001): The Cactus Family, Timber Press, Protland, Oregon
• Chen Yi-ling and Chou Pan-kai. 1982. Rhamnaceae. In: Chen Yi-ling, ed., Fl. Reipubl. Popularis Sin. 48(1): i-vi, 1-169.

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Notes

Identifiers:

• Global Biodiversity Information Facility Taxonkey: 1201766
• Globally Unique Identifier: urn:lsid:ipni.org:names:133499-1
• Zipcode Zoo Species Identifier: 743383

Footnotes:

1. Yilin Chen & Carsten Schirarend "Rhamnaceae". in Flora of China Vol. 12 Page 115,355. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org.
2. Allan D. Zimmerman & Bruce D. Parfitt "Hamatocactus". in Flora of North America Vol. 4 Page 98, 207, 208, 218. Oxford University Press. Online at EFloras.org.