Revision of Spathacanthus
Spathacanthus hahnianus
Thomas F. Daniel
Department of Botany
California Academy of Sciences
Golden Gate Park
San Francisco, CA 94118
|
|
Revision of Spathacanthus Thomas F. Daniel |
|
Generic Descriptions & Key to Species S. hahnianus Acknowledgments & Literature Cited
Figure Legend: |
Spathacanthus hahnianus Baill. Hist. pl. 10: 444. Jan--Feb 1891.---TYPE: MEXICO. Veracruz: Misantla, forêt de la montays Santa Rita, 3 Jul 1866, L. Hahn 349 (holotype: P!). See discussion in Daniel (1995a: 130). Ruellia macrocarpus Sessé & Moc., Fl. mexic., ed. 2. 148. 1894, non Ruellia macrocarpa Wall. (1830).---TYPE: not designated; see discussion in Daniel (1995a: 130). Macfadyena simplicifolia Donn. Sm., Bot. Gaz. (Crawfordsville) 16: 198. Jul 1891. Spathacanthus simplicifolius (Donn. Sm.) Lindau ex Bureau & K. Schum. in C. Martius, Fl. bras. 8(2): 294. 1897. Spathacanthus simplicifolius (Donn. Sm.) Leonard, Proc. Biol. Soc. Wash. 50: 16. 1937, comb. superfl. Spathacanthus donnell-smithii Lindau ex Donn Sm., Bot. Gaz. (Crawfordsville) 20: 293. Jul 1895, nomen illegit. (new name for M. simplicifolia but latter cited as synonym and "specific name dropped as inappropriate"). Spathacanthus donnell-smithianus Lindau, Bull. Herb. Boissier 3: 371. Aug 1895, nomen illegit. (M. simplicifolia cited in synonymy).---TYPE: GUATEMALA. Alta Verapaz: Pansamalá, 3800 ft., Aug 1886, H. von Türckheim 1030 (holotype: US!; isotypes: GH!, K!, M!, US!). Branched shrubs or small trees to 8 m tall, often with many stilt roots. Young stems quadrate to somewhat compressed, pubescent (especially at nodes where trichomes often form dense tufts) with flexuose to antrorsely appressed eglandular trichomes to 1 mm long, soon glabrate. Leaves petiolate, petioles to 45 mm long, blades elliptic to broadly elliptic to obovate-elliptic, (36--) 45--250 mm long, (9--) 17--143 mm wide, 1.3--3.1 (--4) times longer than wide, (rounded to acute to) acuminate at apex, acute at base, adaxial surface glabrous, abaxial surface glabrous or pubescent along major veins with flexuose to appressed eglandular trichomes to 0.5 mm long, margin glabrous. Inflorescence of terminal racemes or a basally branched panicle of racemes to 5 cm long (excluding flowers), rachis nearly glabrous or pubescent with flexuose-appressed eglandular trichomes, often enlarged in fruit; dichasia 1-flowered, sessile (sometimes becoming subsessile in fruit with peduncles to 2 mm long). Bracts triangular to subulate, 1.5--6 mm long, 1--2.3 mm wide, abaxial surface nearly glabrous or pubescent like rachis. Bracteoles triangular to subulate to linear-lanceolate, 1--6 mm long, 0.8--1.5 mm wide, abaxial surface nearly glabrous or pubescent like rachis. Flowers subsessile to pedicellate, pedicels to 7 mm long, 3--3.7 mm in diameter in fruit, glabrous. Calyx green, (18--) 22--43 mm long, 8--14 mm in diameter (measured flat), abaxially glabrous, beaked in bud with beak to 2 mm long, divided into 2 elliptic to ovate-elliptic segments with unequal incisions 16--30 mm long on 1 side and (0.5--) 3--15 mm long on the other, longer incision 0.56--0.87 times as long as calyx (when shorter incision less than 1 mm long the calyx then appearing particularly spathelike), 1 segment generally with 2 triangular lobes 0.4--2 mm long, other segment generally with 3 triangular lobes 0.4--4 mm long, lobes rarely longer and calyx then appearing unequally 5-lobed. Corolla yellow (white fide Ventura 19361 from Veracruz and Holmes 4392 from Honduras), 46--70 mm long, narrow proximal portion of tube 13--20 mm long, 2.5--4 mm in diameter, densely pubescent internally, throat 19--33 mm long, 9.5--16 mm in diameter at widest expanse, limb 22--45 mm in diameter, upper lip 12--19 mm long, lobes elliptic, (5--) 9--10.5 mm long, 4.5--8.5 mm wide, lower lip 15--18 mm long, lobes linear-elliptic to elliptic, 8--15 mm long, (3.5--) 7--8.5 (--11) mm wide. Stamens with longer pair 16--18.5 mm long and shorter pair 12--14.5 mm long, thecae 3.3--4.2 mm long; pollen subprolate to euprolate, 3-colporate, polar diameter 56--64 µm, equatorial diameter 42--43 µm, P:E = 1.31--1.51, exine foveolate to fossulate to rugulate. Style 28--35 mm long, stigma lobes 0.7 mm long. Capsule 43--62 mm long, stipe 27--34 mm long, head 25--28 mm long, retinacula 7--10 mm long. Seeds subcircular to somewhat squarish to deltate in outline, 6.3--9 mm long, 5.7--8 mm wide, 2--2.3 mm thick, surfaces with low verrucose ridges or bumps. Illustrations. Fig. 3; Bot. Gaz. (Crawfordsville) 16: pl. 18, 1891. Phenology. Flowering: throughout the year; fruiting: December--June. Distribution (Fig. 4). Mexico (Chiapas, Oaxaca, Puebla, and Veracruz), Guatemala (Alta Verapaz), and Honduras (Yoro); in floodplains and along arroyos in lowland rain forests, lower montane rain forests, mesophytic montane forests, and oak forests; 100--1350 m. This species of the Caribbean slope of southern Mexico and northern Central America was not included by Standley (1926) in his account of the ligneous flora of Mexico. Until recently, the species was known from few Mexican collections and it is still poorly known in Central America. A nearly sterile specimen from Guatemala (mountains E of Tactic on road to Tamahú, P. Standley 71343 at F) was annotated as this species by Leonard and cited by Gibson (1974). The condition of the specimen does not allow for its identification using my key and I am therefore hesitant to include it. Thus, the only known occurrence of this species in Guatemala is represented by the type of Macfadyena simplicifolia. A single collection, noted as having white corollas, is also known from Honduras. White corollas were also noted on Ventura A. 19361 from Veracruz. It remains to be verified whether notations on these two specimens accurately portray a difference in corolla color on some individuals of the species. The racemose inflorescences of S. hahnianus sometimes become more or less thyrsoid in fruit by slight elongation of the region between the bracts and bracteoles (i.e., forming a peduncle). |