Nahuatlea arborescens (Brandegee) V.A.Funk, 2017

Funk, Vicki A., Sancho, Gisela & Roque, Nadia, 2017, Nahuatlea: a new genus of compositae (Gochnatieae) from North America, PhytoKeys 91, pp. 105-124 : 114-115

4. Nahuatlea arborescens (Brandegee) V.A.Funk comb. nov. Fig. 3B

Gochnatia arborescens Brandegee, Zoë 5(9): 163. 1903.

Type.

Mexico. Baja California: Cañón de Santa María, El Juste, 1 Mar 1898, C.A. Purpus s.n. (Holotype: UC 91900; possible Isotypes: K 000502538; GH 00008379; US 00119526).

Note.

Determining what may or may not be type material is difficult; all proposed types are Purpus s.n. collections but there are different collection dates and locality information. The Holotype is one of two different collections mounted on the same sheet one of which is annotated as "n. sp." and “type”. That specimen also has a hand-written note that says "The year doubtless 1901 RM" indicating that the date on the sheet January-March 1898 is not correct. The information found on the three possible isotypes is nearly identical (Lower California, San Felipe, Cape Region Lower California, Jan-Mar 1901) but the information is different from the locality information on the Holotype. All of the "type material" specimens are the same species so there is little doubt that this is the correct name for this entity but someone more familiar with the work of Purpus (who seems to have confusing dates and numbers) and Brandegee will need to investigate this further to determine if the three listed specimens are actually isotypes.

Description.

Tree 3-8 m tall, trunk 20-30 cm in diameter; leaves chartaceous, blades 3.5-6.5 cm × 2.5-4.5 cm, ovate to elliptic, cuneate or rounded at base, glabrescent on both faces; heads short-pedunculate, solitary or more usually in loose clusters of 2-20 at apex of branches, few clusters per plant; involucre cylindrical to narrowly ob conic depending on age, 10-15(20) mm tall × 6-8 mm wide at anthesis, bracts in 8-10 series, glabrous; flowers 13-20 per head; corollas yellowish, 12 mm long; anther base caudate, tails ca. 3 mm long, entire; pappus ca. 11 mm long, bristles slender, biseriate.

Remarks.

Cabrera (1971) and Jervis (1954) disagree somewhat on the size of the leaf blade: Cabrera lists it as 35-65 mm × 25-45 mm and Jervis has 5 cm × 3-4 cm. Specimens available to us agree with the range given by Cabrera.

Distribution.

Mexico: known only from Baja California Sur.

Figures

Figure 3. Images of four type specimens: A Nahuatlea arborescens (UC holotype) B N. smithii (K lectotype) C N. obtusata (US holotype) D N. hypoleuca (G holotype). [Furnished by the respective herbaria.]