Monographs Details:
Authority:

Luteyn, James L., et al. 1995. Ericaceae, Part II. The Superior-Ovaried Genera (Monotropoideae, Pyroloideae, Rhododendroideae, and Vaccinioideae P.P.). Fl. Neotrop. Monogr. 66: 560. (Published by NYBG Press)
Family:

Ericaceae
Synonyms:

Arctostaphylos mucronifera DC., Arctostaphylos attenuata var. brachymischa Loes., Arctostaphylos glaucescens Kunth, Comarostaphylis mucronifera (DC.) Klotzsch
Description:

Species Description - Erect, evergreen or facultatively drought-deciduous shrubs to small trees to 10 m tall and 25 cm dbh, base to 32.3 cm diam.; bark peeling or flaking, gray or brown to reddish-orange; young twigs usually hirtellous, with stalked, swollen-headed, and glandular trichomes, eglandular trichomes also present. Leaves not coriaceous or only slightly so, narrowly elliptic to narrowly oblong or oblong, plane to slightly revolute, 3.0-9.5 × 0.6-3.0 cm, base cuneate, apex obtuse to acute, sometimes mucronate, margins entire or subentire, upper surface glabrous, glabrate, or with scattered trichomes, lower surface glabrous or with eglandular trichomes, usually glaucous; midrib pubescent, trichomes glandular or not; petioles 2.0-6.5 mm long, usually glandular hirtellous. Inflorescences unbranched (branched), 3.3- 10.7 cm long; rachis, pedicels, bracts, bracteoles, and calyx subglabrous to tomentose or hirsute, the trichomes usually stalked, swollen-headed, and glandular, or eglandular; floral bracts narrowly ovate to ovate, navicular or carinate, 1.6-4.5 × 1.3-2.1 mm, ciliate; pedicels 0.5-2.2 cm long; bracteoles basal to distal, 1.2-2.5 mm long, ciliate. Flowers with calyx lobes long-triangular to ovate-triangular, 1.4-2.8 × 1.0-2.4 mm, acute to acuminate, ciliate, trichomes glandular or not; corollas bright to deep red (rarely pink?), 5.0-10.0 x 4.0-7.1 mm, glabrous, lobes 0.8-2.0 × 1.4-2.6 mm; stamens 2.8-3.8 mm long, filaments 2.6-3.6 mm long, villous (glabrous? fide type description), anthers 1.3-1.7 × 0.7-1.0 mm, spurs 0.3-0.8 mm long; ovary glabrous or pubescent; style 3.7-5.6 mm long, glabrous. Fruit drupaceous, 5-7 mm in diam., red when immature, dark purple to black at maturity; seeds 2.0-2.4 × 1.0-1.4 mm, surface reticulate.

Discussion:

While Comarostaphylis glaucescens is a distinct species characterized by its red corollas, entire, usually non-coriaceous leaves, tree-like growth form, and rather long pedicels, it is a taxon whose circumscription has been quite confused. The species was originally described (Kunth in Humboldt et al., 1819) as having glabrous filaments, and both Small (1914) and Standley (1924) emphasized this character in their keys. However, while I have seen only photographs of the holotype (and consequently have no information on the filaments), no other specimen of C. glaucescens is known with glabrous filaments. Because of this apparent error, few of the abundant specimens of this species have been correctly identified. Its closest relationships are with C. sharpii, the only other red-flowered species in the genus, and C. polifolia, with which it possibly hybridizes. Comarostaphylis glaucescens differs from C. sharpii in having typically unbranched (vs. highly branched) inflorescences, villous (vs. glabrous) filaments, smaller, less coriaceous leaves, and a more treelike (vs. shrubby) habit. Comarostaphylis polifolia differs from C. glaucescens in a number of characters including the white to pink corollas, coriaceous, re volute leaves, shrubby growth form, and shorter pedicels of the former. The relationship of C. glaucescens and C. polifolia has been discussed by Diggs (1981, 1986b, 1987).

Presumably named for the often strikingly glaucous or glaucescent abaxial leaf surfaces.

Pollination: Pollination studies (Diggs, unpubl, data) indicate that bumblebees and hummingbirds are the main pollinators. Repeated visits by Amazilia tzacatl, Cynanthus latirostris, and Hylocharis leucotis were observed, with individuals visiting numerous flowers, often on a number of different inflorescences. While it is not surprising that hummingbirds visit the bright red corollas, this is the first report of such activity in the genus. However, the main pollinators appear to be bumblebees, which visit frequently and stay a long time. Preliminary reproductive studies using bagging experiments indicate that self-fertilization can occur. Flowering throughout the year, but more commonly Apr-Aug; typically fruiting (Jun-)Jul-Dec.

Distribution and Ecology: (Fig. 12) and ecology. Comarostaphylis glaucescens occurs in the mountains of Mexico, from Oaxaca extending north and west as far as San Luis Potosi, Jalisco, and Sinaloa. The species is found in rather dry Quercus-Pinus forests at 1525-2600 m elevation. Associates include Arbutus xalapensis, Arctostaphylos pungens, Buddleja sp., Bursera cuneata, Clethra sp., Dodonaea vis-cosa, Pinus cembroides, P. engelmannii, P. lumholtzii, P. oocarpa, Quercus macrophylla, Q. resinosa, and Vaccinium sp. The species is sometimes quite abundant and can be one of the vegetational dominants in some localities. Field observations indicate the species is quite tenacious in its soil-binding ability and might prove useful in erosion control. Comarostaphylis glaucescens is apparently the only species in the genus that is facultatively drought deciduous. Numerous specimens are known which lack mature leaves but were fully viable when collected, as evidenced by the presence of immature inflorescences or unexpanded leaves. Correlated with this character is the relatively uncoriaceous leaf texture typical of the species.

Distribution:

Mexico North America| Aguascalientes Mexico North America| Durango Mexico North America| Guanajuato Mexico North America| Guerrero Mexico North America| Jalisco Mexico North America| México Mexico North America| Michoacán Mexico North America| Morelos Mexico North America| Nayarit Mexico North America| Oaxaca Mexico North America| San Luis Potosí Mexico North America| Sinaloa Mexico North America| Zacatecas Mexico North America|

Common Names:

madroño, madroño chino, pingüica, sob nîd, tepemesquite