Montanoa tomentosa

General description:

Montanoa tomentosa was first described by Cervantes in La Llave & Lexarza in 1825. This became Montanoa tomentosa subsp. tomentosa when V. A. Funk revised the classification of Montanoa in her 1982 publication. At the same time, she reclassified M. microcephala as M. tomentosa subsp. microcephala and combined M. rosei and M. gentryi into M. tomentosa subsp. rosei. She was also able to combine several other species of Montanoa into one subspecies, M. tomentosa subsp. xanthiifolia. This new classification scheme was revealed by studying the correlation between the variation in leaves and moisture regimes.

Cytology:

The chromosome number of Montanoa tomentosa is n = 19. (Funk, 1982.)

Distribution:

The species spans a vast portion of Mexico into Central America, but the subspecies have more localized populations. Montanoa tomentosa subsp. tomentosa grows in Central Mexico, subsp. microcephala in Oaxaca and Sierra Madre del Sur, subsp. rosei in Sonora and Sinaloa, Mexico and subsp. xanthiifolia from Jalisco to Costa Rica. (Funk, 1982.)

Habitat:

Each subspecies of Montanoa tomentosa has a slightly different niche. Subsps. tomentosa and xanthiifolia prefer xeric to semi-xeric thorn forests and deserts, roadsides and stream banks. Subsp. tomentosa is usually found between 1900 and 2100 m while subsp. xanthiifolia is usually between 1000 to 1500 m. Subsp. microcephala prefers a slightly more moist environment, from semi-xeric to slightly mesic. It can be found on drained roadsides and slopes from 800 to 1850 m. Subsp. rosei grows in deciduous thorn forests, ditches, on roadsides and hillsides 100 to 600 m. (Funk, 1982.)

Phenology:

All four subspecies have distinct flowering and fruiting periods. Montanoa tomentosa subsp. tomentosa flowers from August to October and fruits from September to November and subsp. microcephala flowers July to November and produces fruit October to December. Subsp. rosei flowers in the winter, from Decemer to March, and produces fruits from January to April. Finally, M. tomentosa subsp. xanthiifolia has the longest flowering period, from August to January, and the longest corresponding fruiting period, September to February. (Funk, 1982.)

Montanoa tomentosa

Diagnostic description:

Much branched shrubs 1-3 m tall. Stems terete, brown, herbaceous parts moderately to densely pubescent, hairs 2 mm long. Leaves highly variable; petioles 1.5-4.0 cm long, with or without auricles and wings, moderately to densely glandular and pubescent, hairs 2 mm long; blades often deltoid or ovate (Figs. 10, 11, 13, 26, 27, 29), 3-20 cm long, 1.5-15.0 cm wide, apex acute to acuminate, margin serrate to irregularly dentate, unlobed to 3-5-lobed, adaxial surface moderately to densely pubescent, hairs pustular, abaxial surface sparsely glandular to densely pubescent, hairs 2 mm long. Peduncles 1.0-3.5 mm long, moderately to densely glandular and pubescent, hairs 0.25-2.0 mm long. Heads erect, 0.3-0.8 cm diam in flower, 0.5-1.2 cm diam in fruit, extremely numerous in dense cymose synflorescences in oppositely and alternately branched compound corymbs. Phyllaries (Fig. 31A, B) 4-6, uniseriate, subequal, ovate-lanceolate, 2.5-5.0 mm long, 1-2 mm wide, green to dark green, apex acute to acuminate, mucronate, margin ciliate, entire, abaxial surface sparsely to densely glandular and pubescent, hairs 0.5-1.5 mm long, adaxial surface glabrous. Ray florets 0-6; corollas cream to white, ligules ovate to obovate to oblanceolate, 3-5(-9.5) mm long, (1.25-)2-4(-5) mm wide, apex truncate to rounded, with or without 1-2 notches and with clusters of round tipped hairs, adaxial surface essentially glabrous, abaxial surface sparsely to moderately glandular, tube (0.5-)1.0-1.5(-2.25) mm long, 0.5 mm diam, glabrous to sparsely pubescent, hairs less than 0.5 mm long. Disc florets (Fig. 31C, D) (3-)8-9(-17); corollas light to deep yellow, tube 1-2 mm long, 0.5-1.0 mm diam, glabrous to sparsely pubescent, throat cylindrical, 1.0-1.25 mm long, 0.5 mm wide, sparsely pubescent, hairs less than 0.5 mm long, lobes 5, 0.5-1.0 mm long, 0.5-0.75 mm wide, apex acute, with clusters of round tipped hairs; stamens with filaments 1.2-3.5 mm long, 0.2 mm wide, anthers not fully exserted from corolla, thecae yellow to brown, 1.25-1.5 mm long, 0.5 mm wide, apical appendages yellow, acute, 0.5-0.6 mm long, 0.5 mm wide, abaxial surface of apical appendages and thecae with or without glands; styles (Fig. 31E, F) yellow, (4.5-)5.5(-7.5) mm long, enlarged at base, stigmatic surfaces yellow to brown, 1 mm long, apical appendages yellow, acute, 0.5-0.6 mm long, 0.5 mm wide, abaxial surface of stigmatic area sometimes glandular. Pales at anthesis more or less pentagonal to triangular (Fig. 31G, H), 2-6 mm long, 1-4 mm wide, light yellow to yellow with dark bands near midrib, apex long-acuminate, light or dark, indurate, margin ciliate, entire, abaxial surface moderately to densely glandular and pubescent, hairs 1-5 mm long, adaxial surface glabrous; pales at fruiting persistent, obtrullate to obtriangular (Fig. 31I, J), 4.5-10.0 mm long, 1-4 mm wide, indurate with inconspicuous parallel veins, stramineous, apex tapering, sometimes recurved and indurate, margin ciliate, entire, abaxial surface moderately to densely glandular and pubescent, hairs 0.5-4.0 mm long, adaxial surface glabrous. Achenes usually only one maturing per head, brown-black, 2.5-3.5 mm long, 1.0-1.5 mm diam, smooth. Chromosome number, n = 19.

Funk, V. A. "The Systematics of Montanoa (Asteraceae, Heliantheae)" in Memoirs of the New York Botanical Garden. Vol. 36. The New York Botanical Garden. Bronx, NY. 1982.

Morphology:

The key below is taken from The Systematics of Montanoa (Asteraceae, Heliantheae). (Funk, 1982.)

1. Petioles winged to base; Oaxaca, Mexico...........................................................1b. subsp. microcephala.

1. Petioles never winged to the base.

2. Leaf blades ovate, margins never lobed; disc florets 3-9, usually 6-7; Sonora and Sinaloa,

Mexico.................................................................................................................1c. subsp. rosei

2. Leaf blades triangular or pentagonal, usually lobed; disc florets 3-17, usually 9-12; Jalisco,

Mexico to Costa Rica.

3. Leaf blades usually longer than broad, dark green, at base truncate or cordate, with

margins usually irregular; central Mexico to Oaxaca; 1900-2800 m........1a. subsp. tomentosa

3. Leaf blades usually as broad as long, bright green, base with partially winged petiole

or acute, with margins usually entire or 3-5 lobed; Jalisco, Mexico to Costa Rica; up

to 1800 m........................................................................................................1d. subsp. xanthiifolia

Taxon biology:

Kingdom Plantae

Subkingdom Tracheobionta

Superdivision Spermatophyta

Division Magnoliophyta

Class Magnoliopsida

Subclass Asteridae

Order Asterales

Family Asteraceae

Tribe Heliantheae

Genus Montanoa

Subgenus Montanoa

Section Montanoa

Species tomentosa

Compositae

Taxonomy

Montanoa tomentosa

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Montanoa tomentosa

Montanoa tomentosa

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Taxonomy

Montanoa tomentosa

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