Rhamnus pompana M.C.Johnst. & L.A.Johnst.

Authority

Johnston, Marshall C. & Johnston, Laverne A. 1978. Rhamnus. Fl. Neotrop. Monogr. 20: 1-96. (Published by NYBG Press)

Family

Rhamnaceae

Scientific Name

Rhamnus pompana M.C.Johnst. & L.A.Johnst.

Type

Type. Pringle 8079 (M: isotypes, A, F, L, MICH, MO, NY, POM, TEX, UC, US, W) Mexico, Veracruz, near Jalapa, fl, 31 Mar 1899.

Description

Latin Diagnosis - Frutices pubescentes crispati-villosi pilis erectis raro rectis ad 0.3 mm longis; cataphylla evoluta; laminae foliorum (2.5-)5.0-8.5(-14.0) saepissime ca 5.6 cm longae, (1.4-)1.9-3.7(-6.5) saepissime ca 2.7 cm latae, 1.7-3.0 (saepissime 2.4)-plo longiores quam latiores, margine serratae crenataeve dentibus nonnunquam prominentibus ad 3 mm longis interdum nigromucronatis, plus minusve concolorae supra raro glabrae subtus modice pubescentes; petioli 4-14 mm saepissime 10-11 mm longi; stipulae caducae; inflorescentia sessiles axillares 3-12(-14)-florae; flores 5-meri hermaphroditi; cupula floralis per anthesin 1.0(-l .5) mm longa (1.5-)2.0 mm lata; sepala 1.0(-1.5) mm longa, ca 1.0 mm lata; petala saepe 0.6-0.8 mm longa, ovarium 3-loculare pubescens; fructi (4-)5-6(-7) mm diametro pubescentes trispermi.

Description - Shrub or small tree to 6.0 m (Balls 4729 states "round-headed trees to 40 feet" or 12 m). Pubescence of the entire plant is crisply villous, ie, hairs erect but seldom straight, rather irregular in configuration, not matted, up to 0.3 mm long, pale. Stem pubescence decreasing with age from moderate (rarely dense) amount on younger parts to none on older parts. Bud scales absent. Stipules subulate, (1.0-)2.0-2.5(-4.0) mm long, usually dark, moderately or sometimes densely pubescent, caducous; petioles (4.0-)cal0.0-11.0(-14.0) mm long with sparse to dense but usually moderate pubescence; leaf-blades membranaceous, not leathery, (2.5-)5.0-8.5(-14.0) (averaging ca 5.6) cm long, (1.4-) 1.9-3.7(-6.5) (averaging 2.7) cm wide, mostly elliptic, somewhat ovate, or rarely obovate, 1.7-3.0 (averaging 2.4) times longer than wide; base rounded or cuneate (often broadly so); apex acuminate (acumen slender and sometimes up to 2.0 cm long) or rarely acute; margin plane or revolute, usually serrate or sometimes crenate, teeth may be salient and up to 3.0 mm long, each tooth with or without a dark mucro at the tip; above green with sparse to moderate (rarely glabrous) amount of often appressed hairs, midrib usually yellowish and sulcate but not deeply so, it and secondary veins with moderate to moderately dense pubescence (rarely glabrous), minute veins almost invisible; beneath about the same color as above (excepting Balls 4729) with moderate (rarely less) amount of hairs, midrib and secondary veins usually yellowish and raised with moderate (rarely sparse) pubescence which may be more than or similar to surface, mostly on lateral margins and sometimes conspicuously dense where secondary veins arise from midrib, minute veins sometimes dark but not strongly so; secondary veins (6-)7-10(-12) pairs. Inflorescence an axillary glomerule of 3-12(-14) flowers; peduncle absent; pedicels at anthesis slender and (2-)3-5(-6) mm long; flowers 5-merous; floral cup 1.0(-1.5) mm long and (1.5-)2.0 mm broad; sepals deltoid, 1.0(-1.5) mm long, ca 1.0 mm wide; external floral parts with sparse to dense but usually moderate pubescence externally; petals (0.5-)0.6-0.8(-1.0) mm long, obovate, claw usually much reduced, emarginate, amplectant; anther only rarely apiculate; ovary trimerous, from moderately to densely pubescent, style ca 0.3 mm long, minutely 3-coccous at apex. Fruits with pedicels (4.0-)7.0-9.0(-10.0) mm long, nearly globose, (4-)5-6(-7) mm in diam, at first green then turning red and finally black (usually brown in prepared specimens), with moderate (occasionally sparse) amount of pubescence, 3-stoned.

Discussion

Rhamnus pompana is named to honor Dr. Arturo Gomez Pompa, one of the pre-eminent botanists of Mexico and a leader in the project to compile a flora of Veracruz, the state in which this species is best developed. The species is an element of the higher zones of the “Huasteca,” the too heavily populated and utilized region of high relief on the eastern slopes of the Sierra Madre Oriental. The few remaining patches of forest in this upper zone enjoy almost continuous year-long fog and clouds and moderate temperatures, with very rare light winter frosts.

Distribution

In east central Mexico. Often on slopes, sometimes along ravines, always in moist wooded situations with sweet gum, oak, and/or pine at 1200-2000(-2150) m alt. Flowering March through May; fruits develop¬ing as early as mid-April.

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