Vegetative key and description of tree species of Santa Rosa

‘shattered glass’ surrounding a blank region near the midrib. Secondary venation on upper surface is not apparent. Habitat and Phenology: Common understory treelet apparently more abundant in dry areas, cliffs, and mesa tops of deciduous forest. Similar Species: E. rotundifolium.

Erythroxylon rotundifolium Lunan; ERYTHROXYLACEAE. Description: Small treelet to shrub. Distinctively round, simple, alternate leaves 1-2.5 cm in length, in clumps along stem.

Leaf underside is pale to light green, with very faint secondary venation. Habitat and Phenology: Understory plant of dry deciduous forest. Rare, although locally common in some parts of Santa Rosa. Similar Species: E. havanense.

Eugenia hypargyrea Standl.; MYRTACEAE. Description: Small tree. Simple and opposite ovoid leaves, 6-9 cm in length, with leaf margin tending to curl downwards. The upper surface is glossy green while the underside has a pale sheen from trichomes. The leaves have a felt-like feel. Flowers are small (1 cm diameter), with four white petals. These petals are retained by the up to 15 mm long ovoid fruit. Fruit is red to deep purple and fleshy when ripe. Habitat and Phenology: Tends to be found in young forest and regenerating pasture.

More common near the coast. Similar Species: Eugenia salamensis (larger leaves, usually with punctations; larger fruit); Rehdera trinervis (leaves have asymmetrical trinervate venation, leaf margin does not curl under).

Eugenia salamensis Donn. Sm. "Fruta de pava"; MYRTACEAE. Description: Small to medium sized tree. Opposite, planar, round to elliptic shaped leaves, usually 12-20 cm in length. Scattered tiny white hairs more common on the underside. When held up to bright light leaves usually have numerous, tiny punctations (there may be exceptions). Leaves tend to have a slightly lobed leaf base. Fleshy oblong fruits up to 30 mm in length, varying in color from yellow-orange to purple. Habitat and Phenology: Usually found in secondary forest and regenerating pasture. Fruit late wet season. Similar Species: E. hypargyrea (smaller leaves); Psidium guineense (Myrtaceae, not listed here; tends to have pubescent leaves, with a slight point on the tip and a tapered leaf base).

Euphorbia schlechtendalii Boiss.; EUPHORBIACEAE. Description: Small to medium sized tree. Simple, glabrous, oval leaves, usually 4-7 cm in length, including a 1-3 cm long petiole.

Leaves are arranged in distinctive whorls of 5-7 (occasionally 8). Leaf underside is pale.

Copious white latex from broken petioles and stems. Trunk with peeling thin papery bark.

Habitat and Phenology: Rare tree.

Exostema mexicanum A. Gray; RUBIACEAE. Description: Medium sized tree. Simple, opposite, glabrous leaves, usually 11-18 cm in length, with distinctive interpetiolar stipules at leaf bases. Stipules are triangular with a distinctive longitudinal ridge. Young branches have a distinctive ‘Y’ forking branching architecture. Large trees have tan bark that peels in small strips giving individuals a ‘shaggy’ appearance. When young, however, bark is smooth (quite different from adult trees). Blooms sprays of several small white flowers. Infructescenses of many 1-2 cm long oblong pointed fruits. Habitat and Phenology: Common deciduous, medium-sized tree in deciduous forest. Flowers mid wet season. Mature fruits late wet season. Similar Species: Coutaria hexandra.

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