Alfaroa mexicana
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Alfaroa mexicana |
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Alfaroa mexicana is a Central American tree from the walnut family(Juglandaceae).
features
Vegetative characteristics
Alfaroa mexicana reaches heights of up to 35 m and a diameter of up to 1 m at breast height . It forms medium-sized buttress roots that reach up to 1 m on the trunk. The bark is pink throughout. The wood is white and has scattered pores. The pith of the branches is firm. The buds are bare.
The leaves are opposite and are pinnate in pairs. The petiole is 2.5 to 5.2 cm long, the rachis 6.7 to 13.3 cm. The 8 to 12, rarely up to 18 leaflets are opposite to almost the same and on 4 to 8 mm long petioles. The blades are 3 to 5 times longer than wide, 7.5 to 17.5 cm long and 1.5 to 4.0 cm wide. The leaf base is symmetrical to asymmetrical, rolled back on one or both sides. The leaf margin is whole. Young leaves are pink to yellow-green and folded together so that the underside is exposed. The ripe leaves are leathery, the upper side is dark green, hairless or with a few buttery yellow, shield-shaped scales. The underside is light green and covered with buttery yellow and transparent shield-shaped scales. In addition, there are dense tufts of short hair at the base between the midrib and the leaf margin. Individual star hairs also occur.
Inflorescences and flowers
The trees are monoecious . However, there is a tendency for male, female and hermaphrodite individuals to occur. The kittens are terminal, rarely on the side of this year's shoots. If male and female flowers occur together, they form an androgynous panicle : the female catkin is then at the end, underneath there are 1 to 3 pairs of male catkins opposite. If the male kittens stand alone, they stand to the side of last year's or this year's shoots. More often, however, they form groups of opposite branches, each of which in turn carries 1 to 3 opposite pairs of kittens.
The male flowers are too many (up to 40) on the catkins and are 2 to 3 mm in size and usually sessile. The outer sides are covered with buttery yellow and transparent shield-shaped scales. The trilobed bract is cup-shaped and partially encloses the young flower. The flower cup is rounded. There are two bracteoles and two, rarely three sepals . There are 8 to 12 stamens in a row, stamens are practically not formed. The anthers are bithekish, glabrous, and open with longitudinal slits.
The female flowers are cross-opposed to 1 to 10 per ear . They are 5 to 6 mm in size, sitting, the lower half is enclosed by the bract. This is covered on the outside with overlapping shield-shaped scales and has three lobes. Bract oils are largely absent. The calyx tube is with the under constant ovary merged. The ovary is square in cross section. The upper part of the calyx is covered with shield-shaped scales and deeply four-lobed. The lobes are 3 to 4 mm long and protrude 1 to 2 mm above the scar . One stylus is missing. The scar is rather spherical, with a larger furrow along the point where the two carpels are fused.
fruit
The fruit is up to 5.5 cm long and 4.2 × 3.7 cm in cross section. The calyx remains when the fruit is ripe and is 5 to 7 mm long. The bract is pressed against the base of the fruit and is 8 to 12 mm in diameter. The shell is ribbed from base to tip, slightly warty, glabrous and up to 7 mm thick. It does not open and fits tightly to the nut inside . The shell is ribbed and 1 to 4 mm thick. The division of the nut inside is complex, with primary, secondary, tertiary and incomplete quaternary partitions, so that in the lower half of the nut there are 8 compartments, sometimes 16 compartments, which merge over half to form four compartments and one at the top.
Seedlings
The germination takes place hypogeous. The seedlings have a long, slender taproot . The first two leaves that appear outdoors are opposite, the plants vivid pink. The next following leaves are alternate and pinnate, the later then opposite and pinnate. The leaf margin is always whole.
distribution
Alfaroa mexicana is limited to a small area in Mexico : it is only known from the two volcanoes San Martín and Santa Marta in the Sierra de los Tuxtlas in the state of Veracruz . On the slopes of these mountains it grows on the southern slopes together with Celtis , Juglans , Liquidambar , Quercus , Saurauia , Talauma and Trophis . It is sometimes common on the more humid northeast slopes and grows here with Oreopanax , Hedyosmum and Ardisia .
The species is listed as vulnerable by the IUCN .
supporting documents
- Donald E. Stone: New World Juglandaceae: A New Species of Alfaroa from Mexico . American Journal of Botany, Vol. 55, 1968, pp. 477-484. (JSTOR)
- Héctor V. Navare Flores: Juglandaceae . Flora de Vera Cruz, Volume 31, Instituto Nacional de Investigaciones sobre Recursos Bióticos, Xalapa 1983, ISBN 84-89600-51-1
Individual evidence
- ↑ alfaroa mexicana in the endangered Red List species the IUCN 2008 Posted by: M. González-Espinosa, 1998. Retrieved on January 12 of 2009.