1973] FAY: NEW SPECIES OF FROM MEXICO 197

Additional specimens examined:

MEXICO: : along Pan American Hwy., 3 mi E of Chiapas- border, 14 Oct 1962, Cronquist 9669 (NY); along Hwy. 190, 11 mi SE of Tapanatepec, 20 Oct 1965, Breedlove & Raven 13719 (NY). Verbesina sousae appears to be most closely related to Verbesina robinsonii (Klatt) Fern. (= Otopappus alternifolius Robins.). The latter species, however, has smaller, subsessile leaves (up to 13 cm long, 4 cm wide) that are whitish and densely tomentose beneath; a narrowerinvolucre (1-1.5 cm wide); and achenes with two awns, the inner of which is broadly winged. V. sousae and V. robinsonii appear to be intermediatebetween Verbesinaand Otopappussensu lato (including Notoptera). Like that of Otopappus, the adaxial awn of the achene in V. sousae is much better developed than is the abaxial, which is completely lacking in V. sousae. The remain- ing awn, however, does not have the characteristic broad decurrent wing found in Otopappus. Furthermore, V. sousae has alternate leaves (anomalous in Otopappus) and an ascending branching pattern in the inflorescence, which differs markedly from the distinctly divaricate one in Otopappus. In this case it seems reasonable to follow the recommendations of McVaugh (1945) on delimiting genera and to maintain the intermediate species in the larger and more diverse Verbesinarather than in Otopappus, where it would significantly alter the generic limits and would tend to detract from the unity of the group. I take pleasure in dedicating this species to Mario Sousa Sanchez, an active stu- dent of Mexican .

Sabazia trifida Fay, sp. nov. (Fig. 4). Planta annua, diffusa vel (in planta minore) simplicicaules, radice palari. Caulis gracilis, basi sparse et paulo retrorse pilosus. Folia opposita, petiolata, lanceolato- rhomboideavel lanceolato-ovata, 3-6 (-11) cm longa, 0.5-3 (-5.5) cm lata, supra et subtus sparse vel modice appresse pilosa. Capitula plerumque numerosa, vel in plantis minoribus tantum 2-4, involucro ca. 3-seriato, hemispherico, phyllariis exterioribus sparse pilosis, basi induratis, apice acutis, herbaceis, phyllariis interioribus minus pilosis, apice acutis vel rotundatis, scariosis, margine superiore ciliatis. Flores radii (8-) 10-15, lamina alba, saepe in juventute subtus purpurascente, ca. 1 cm longa, oblonga, tubo gracili, piloso, ca. 2-3 mm longo. Paleae ca. 3-5 mm longae, scariosae, bifidae vel trifidae per ca. 34 longitudinis, lobis lateralibus quam lobo,medio, brevioribus sed latioribus. Receptaculum manifeste conicum etiam in juventute. Flores disci ca. 100, corolla ca. 3 mm longa, tubo gracili, piloso, faucibus late cylindricis. Achaenia elliptica, nigerrima, glabra, ca. 1 mm longa et 0.5 mm lata. Pappus ex 3-5 aristis gracilibus,caducis, 1-2 mm longis constans. TYPE: MEXICO: OAXACA: steep, gravelly banks in pine-oak-alder zone, Sierra Madre del Sur ca. 125 km S of Oaxaca, on rd. to Puerto Angel, elev. ca. 2400 m, 8 Nov 1970, Cronquist & Fay 10889 (HOLOTYPE: NY; ISOTYPES: CAS, DUKE, ENCB, F, GH, KANU, MEXU, MICH, MSC, S, TEX, US, UTC). It is interesting to note that the present species possesses deeply trifid pales and shallowly trifid ligules, characters used by Longpre (1970) in segregating the Tricarpha. The pappus in S. trifida, on the other hand, is closest to, that found in . It would be difficult nevertheless to assign S. trifida to either Tricarpha or Selloa because it lacks the broad scarious margins on the outer phyllaries charac- teristic of the former and lacks the linear pales and rosulate habit characteristic of the latter. At present it seems most reasonable to include S. trifida in as a somewhat anomalous species. In my opinion, the intermediate position of S. trifida 198 BRITTONIA [VOL. 25

1cm

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flower; F, achene.~~/ / 1973 ] FAY: NEW SPECIES OF ASTERACEAE FROM MEXICO 199 tends to blur the already tenuous distinction between Sabazia and Tricarpha although such a position probably does not affect the generic status of Selloa, which is principally defined on characters other than those of its pappus. Within Sabazia sensu lato (including Tricarpha) this is the fourth annual species and is the only one to combine deeply trifid pales, a setifoirm pappus, and outer phyllaries with herbaceous margins. LITERATURE CITED Longpre, E. K. 1970. The systematics of the genera Sab-azia, Selloa and Tricarpha (Com- positae). Publ. Mus. Michigan State Univ., Biol. Ser. 4: 287-383. MeVaugh, R. 1945. The genus Triodanis Rafinesque and its relationships to Specularia and Campanula. Wrightia 1: 13-52.