Pereskia stenantha F.Ritter
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Authority
Leuenberger, Beat E. 1986. Pereskia (Cactaceae). Mem. New York Bot. Gard. 41: 1-140.
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Family
Cactaceae
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Scientific Name
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Description
Species Description - Shrub or small tree, 2-4(-6) m, branching at or from near the base; trunk to ca. 15 cm diam. in the few large specimens seen; main shoots erect and arching, with epitonous branching; bark gray, smooth or longitudinally fissured; distal twigs ca. 4-6 mm thick, with few to many stomata, grayish-brown after periderm formation. Areoles rounded, 2-5 mm in diam. on twigs, larger on main shoots, accrescent to 15 mm diam. on trunk, with short and dense, pale grayish-brown tomentum of uniseriate trichomes 2-3 mm long, producing spines and 1-3 brachy-blast leaves. Leaves variable in shape and size, obovate to elliptic, often folded upward along the midrib, (5-)7-11 (-15) x (2-)4-6(-9) cm; petiole 2-10 mm long, thick when fresh and with basal spur-like rim below; blade 0.6-1.0 mm thick, fleshy; base cuneate to attenuate; apex broadly acute to rounded, often recurved; midrib prominent below; lateral veins 5-7, patent, often inconspicuous in fresh leaves. Spines 0-7 on twigs, fasciculate to spreading, stiff, 1-5 cm long and to 1 mm thick, increasing in number to ca. 20 on main shoots and up to 40 on trunk, to 5 cm long and 1.5 mm thick, brown to grayish-brown, base dark red when fresh on young spines. Inflorescence terminal, densely cymose-paniculate by proliferation, the receptacle of the terminal flower, 5-15 cm in diam., to ca. 15-flowered, with leafy bracts; flowers sometimes solitary, terminal or axillary. Flowers perigynous to epigynous, opening very little, campanulate-urceolate, 20-35 mm long and 10-20 mm in diam., odorless; flower buds orange-red; flowers orange-red without, pink within; pedicels 1-3 mm long, hardly distinguishable from the turbinate receptacle; receptacle 7-10 mm in diam., bracteate in the upper half; bracts varying in number and size depending on the position of the flower within the inflorescence; areoles ca. 5-8, with short grayish-brown tomentum, the upper ones only visible as tufts of tomentum on both sides of the erect upper bracts but without longer hairs visible along the margin of the bracts; lower bracts 3-5(-7), usually five on the distal flowers and calyx-like, spreading, 5-20(-40) x (2-)4-10(-30) mm, thick, fleshy, green, with broad base and obtuse apex; upper bracts (1-)3-5(-6), erect, broadly triangular, 4-5 x 5-7 mm, keeled, fleshy, green to reddish; sepaloids 4-5, erect, ovate to narrowly ovate, to ca. 18 x 9 mm, with broad base, to 1.5 mm thick and fleshy, concave, apex acute or rounded with a point, red to orange-red, with a purplish-pink tinge usually at the margin only and particularly in bud, more reddish than in P. bahiensis; petaloids 6-8, erect, imbricate, spreading at the tip only, linear-lanceolate, 20-25 x 4-12 mm, the inner ones narrower than the outer; apex acute to broadly acute, blade pink to purplish-pink, base ca. 1 mm thick when fresh, pale pink; stamens ca. 140, 12-15 mm long, erect, surrounding the slightly longer style and stigma lobes, not attaining the throat of the corolla; filaments in ca. 2 rows, white, their base slightly prominent at the level of insertion above the conspicuous 1.5-2 mm high nectarial wall; anthers ca. 1 x 0.3 mm, pale yellow; pollen mostly 12-colpate, mediumsized, tectum with fine perforations and rather small spinules; ovary half inferior to inferior, locule ca. 3 mm in diam., floor concave, roof with septal ridges, placentae parietal; style 13-20 mm long and 0.8-1 mm thick, white, base widened into the conical ovary roof of 3-5 mm diam.; stigma lobes 4-7, 4 mm long, slender, suberect to spreading. Infructescence a densely cymose-paniculate cluster of proliferating fruits, erect or arching at maturity, to 20 cm in diam., with few to 15 fruits, or fruits solitary. Fruit variable, 3-7 x 2-6 cm, pyriform or turbinate and more or less angled, green to yellowish-green when mature; pedicel to 3 mm long; areoles conspicuous, with dense grayish-brown tomentum, rarely spiny with 1-5 spines of 1-3 cm length (only one such specimen seen); bracts obovate, ca. 5-10 mm long or larger leaf-like, usually deciduous at maturity; umbilicus constricted to ca. 5 mm diam., usually filled by the flower remnant and the fleshy upper bracts; fruit wall 5-10 mm thick, containing many mucilage cavities, ovary roof to 15 mm in diam., smooth, green, 5-10 mm thick, with mucilaginous tissue inside; locule broadly obovate, to 25 mm. Seeds ca. 30(-50), obovate, 4.5-5.5 mm long, 3.2-3.6 mm broad and 2.0-2.5 mm thick, smooth, black, glossy; hilum transversely lunate to semicircular, ca. 1 mm in diam., whitish; micropylar nose mostly conspicuous. Seedling (three weeks old) with hypocotyl ca. 20-30 mm long and 2-2.5 mm thick, reddish; cotyledons ovate-elliptic, ca. 30-40 x 15-20 mm, midrib faint, lateral veins 0-2, inconspicuous. Chromosome number: 2n = 22; Leuenberger et al. 3072, cult. hort. Berol. 166-72-83-10 (B).
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Discussion
Type. Brazil. Bahia: Caetité, Ritter 1251 (holotype, U, fide Ritter, but not located there, probably not deposited; figure 3 of Ritter, 1979: 277, shows the type specimen and may serve as lectotype). Local names and uses. Quiabento, espinha de Santo Antonio, flor de cêra. Planted in hedges near Bom Jesus da Lapa, Igaporã and Riacho de Santana but according to local people increasingly replaced by barbed wire because the spines are feared. Specimens of this species were collected in Bom Jesus da Lapa by Zehntner in 1912, and a specimen of P. bahiensis, collected in the same year (Zehntner 639), is annotated with the remark that the plant from Lapa (Zehntner 631) differs in its longer and red-orange flower buds and the flowers which open only a little. However, the specimens and the notes were not sufficient to make the diagnostic characters evident to later workers. They are most striking in fresh flowers, but in specimens dried without special care the flowers of P. stenantha look much like withered flowers or flower buds of P. bahiensis to the observer who has not seen both as living specimens. Ritter recognized the species as new during field observations, probably in 1964, when he discovered several new Cactaceae in southern Bahia (Ritter, 1979, pp. 66-69). He cites Caetité as the type locality, but during a visit to that area in 1983 I found only P. bahiensis in flower and fruit. Local people at Brejinho das Ametistas near Caetité say that two different plants occur in the area. Pereskia stenantha is a remarkable species because it does not seem to differ from P. bahiensis in vegetative characters. Those given by Ritter (1979) (time of spine and leaf formation, color of leaf margin), do not prove reliable from the material I have seen. All the more surprising are the flowers, which are unique in the genus with their urceolate corolla. The flowers are not structurally different, but differ greatly from P. bahiensis in orientation, shape, and color of the sepaloids and petaloids and the larger nectary, all of which suggests a hummingbird pollination syndrome. Ritter (1979) inferred that this is a case of rapid evolution. Unfortunately no observations on pollinators are available yet. Near Bom Jesus da Lapa a shrub of similar habit and shape and color of inflorescence, Jatropha mutabilis (Pohl) Baillon, is easily confused with Pereskia stenantha at a distance.