Heterosperma Cavanilles (1794: 34)

Lizarazu, Mabel A., Scataglini, M. Amalia & Freire, Susana E., 2018, Testing the monophyly of Heterosperma (Asteraceae, Coreopsideae), Phytotaxa 365 (3), pp. 245-258 : 251-255

Heterosperma Cavanilles (1794: 34) .

TYPE SPECIES:— Heterosperma pinnatum Cav.

Geographic distribution and habitat:—W North America to NW South America and Caribbean ( Fig. 4 ); wooded grassland, roadside ditches, and open mountain slopes: 650−4500 m ( Fig. 5 ).

Heterosperma mexicanum (A. Gray) Lizarazu & S.E. Freire , comb. nov. Leptosyne mexicana A. Gray ex Watson (1887: 429) . Coreopsis cyclocarpa Blake (1914 [1913]: 339). TYPE:— MEXICO. Jalisco, Rio Blanco, 17 Sept 1886, E. Palmer 568 (holotype US - 00128148!; isotypes GH - 00009645!, K - 0004979490!,

MEXU - 012220337!, MO - 1840292!, NDG - 60484!, NY - 00180551!, NY - 00180552!, P - 02140481!, PH - 00014921!, US - 00931206!,

YU - 002167!). Fig. 6.

Perennial herbs, erect, 60−70 cm tall, stems numerous from a thick woody base, slightly glabrous to pubescent below. Leaves opposite, sessile, entire, linear to filiform, 20−60 × 1.5−2 mm, glabrous. Capitula in open corymbiform cymes, peduncles 2−7 cm long, glabrous to rarely sparsely hispid. Involucre hemispheric. Phyllaries 2−3 seriate: outer 5−6, narrowly lanceolate, 2−3 × 1.5−2 mm, glabrous, fleshy; inner 8−12, ovate to lanceolate, 5−9 × 4 mm, striate, glabrous, scarious, yellow, reddish and pale on margins. Receptacle convex, paleate; palea oblanceolate, 4−5 × 1.5 mm, obtuse, 3-nerved, membranaceous, glabrous. Ray florets yellow, 8−10, female, fertile, rays 3-lobed, 11−13 × (3–) 5.5−7 mm, 12−14-nerved; tube narrow, with glandular and non-glandular trichomes. Disc florets 15−25(–35), bisexual, fertile; corolla yellow, tubulose, 5-lobed, 3.5−5 mm long, with glandular and eglandular trichomes; anthers 1.5−1.7 mm long, subauriculate at the base, appendages deltate; style arm apices deltate, papillose with long appendages. Cypselae graded monomorphic (sub-heteromorphic), obcompressed, winged, epappose, smooth and glabrous, dark brown to black; ray cypselae orbicular to obovate, 3.5−5 × 2.2−3.5 mm; disc cypselae narrowly orbicular to obovate, 6.5−7 × 5− 3 mm.

FIRGURE 6. Heterosperma mexicanum (A. Gray) Lizarazu & S.E. Freire var. mexicanum . A. Habit. B. Entire leaf. C. Capitulum. D. Palea. E. Ray floret. F. Disc floret. G. Stamen. H. Style branches. I. Ray cypsela. J. Disc cypsela (from Carman 68-120 (TEX).

Geographic distribution and habitat:—Endemic of Mexico (Jalisco, Nayarit, Zacatecas); in grassy oak woods, on granitic or rocky slopes; 1500−2200 m ( Fig. 7 ).

Additional specimens examined:— MEXICO. Jalisco: Near Guadalajara , 4 Oct 1903, Pringle 11546 (SIparatype) ; on rocky slopes of Cerro Etzatlan diretly S of Etzatlan, 9 Sep 1966, Melchert et al. 6359 (TEX) ; in grassy oak woods on granitic slopes overlooking Guadalajara from the west, 15 Sep 1974, Cronquist 11195 (TEX) ; Guadalajara: Route 15, ca 5 mi west Guadalajara between K-693 and K 694, 20 Sep 1968, Carman 68–120 (TEX) ; Nayarit. 105 Km WNW of Huejuquilla, El Alto along road to Jesus Maria near side road to Santa Lucia de la Sierra, 9 Sep 1984, Breedlove 61476 (TEX) ; Zacatecas: 32 km W on Mexican Hwy 41 just S of Jalpa along road to Tlatenango, 8 Sep 1986, Breedlove 63942 (TEX) .

Heterosperma mexicanum (A. Gray) Lizarazu & S.E. Freire var. pinnatisectum (S.F. Blake) Lizarazu & S.E. Freire , comb. nov. Coreopsis pinnatisecta Blake (1914 [1913]: 339). Coreopsis cyclocarpa var. pinnatisecta (S.F. Blake) Crawford (1970b: 166) . Leptosyne pringlei Robinson & Greenman (1895: 155–156) .

TYPE:— MEXICO. Oaxaca: Sierra de San Felipe , 2743 msm, 7Aug 1894, C.G. Pringle 4871 (holotype GH-9648!; isotypes AC-319470!, BKL-162!, BR-5430482!, CM-2442!, E-413827!, GOET-1395!, JE-4599!, M-30051!, MEXU-1220335!, MEXU-1220336!, MO-1840278!, NDG-60486!, NY-180553!, P-2140482!, P-2140483!, P-2140484!, PH-14922!, RSA-1371!, S-G-3608!, TEX-369!, UC-128166!, UVMVT-27580!) .

Leaves pinnatisect, 25–35 × 15–30 mm, petiole 6−8 mm long, segments linear to filiform, 10–15 × 1–1.5 mm.

Distribution:—Endemic to Mexico (Guerrero and Oaxaca). Fig. 7 .

Taxonomic notes:— Heterosperma mexicanum var. pinnatisectum is morphlogically similar to H. achaetum and H. pinnatum in its pinnatisect leaves. It differs by being a perennial plant, with inner phyllaries longer than the outer ones, ray florets 11−13 mm long, disc florets 3.5–5 mm long (vs. plant annual, with inner phyllaries shorter than the outer ones, ray florets (1.5–) 3–4.5 mm long, disc florets 1–1.2 mm long in H. achaetum and H. pinnatum ). Heterosperma mexicanum also resembles H. achaetum in its graded monomorphic (sub-heteromorphic) cypselae.

We agree with Crawford (1970a) who observed that H. mexicanum var. mexicanum (= Coreopsis cyclocarpa var. cyclocarpa ) and H. mexicanum var. pinnatisectum (= C. cyclocarpa var. pinnatisecta ) are very similar morphologically and appear to differ only by a feature of their leaves, with simple linear to filiform leaves in H. mexicanum var. mexicanum , and pinnatisect cauline leaves in H. mexicanum var. pinnatisectum .

Figures

FIGURE 4. Geographic distribution of Heterosperma Group A (red circles) and Group B (violet circles).

FIGURE 5. Heterosperma. A−F. H. nanum. A−B. Habit. C. Floriferous stems. D. Capitulum showing ray and disc florets. E. Capitulum showing inner and outer phyllaries. F. Capitulum showing cypselae. G−H. H. ovatifolium. G. Capitulum showing maturate cypselae. H. Habit [B. from Lizarazu & Satto 125 (SI). C. from Lizarazu & Satto 142 (SI). G−H. from Lizarazu 87 (SI). F. from Zuloaga et al 14207 (SI), and D−E, from Zanotti et al. 863 (SI)]. Photo credit: Lizarazu 2017 (A−C, G−H), Zuloaga 2013 (F), and Zanotti 2016 (D−E).

FIGURE 7. Distribution of Heterosperma mexicanum: H. mexicanum var. mexicanum (squares), H. mexicanum var. pinnatisectum (triangles).