Myrceugenia myrcioides (Cambess.) O.Berg

  • Authority

    Landrum, Leslie R. 1981. A monograph of the genus Myrceugenia (Myrtaceae). Fl. Neotrop. Monogr. 29: 1-137. (Published by NYBG Press)

  • Family

    Myrtaceae

  • Scientific Name

    Myrceugenia myrcioides (Cambess.) O.Berg

  • Synonyms

    Eugenia myrcioides Cambess.

  • Description

    Species Description - Small tree 1.5-6 m high; hairs reddish-brown or yellowish-brown to greyish-white, dibrachiate, symmetric or nearly so, usually appressed; twigs densely pubescent when young, glabrescent with age, the bark sometimes falling in thin sheets; leaves usually elliptic, elliptic-ovate or lanceolate, less often elliptic-obovate or oblanceolate, 3.5-16 cm long, 1-7 cm wide, 1.8-3.6 times as long as wide, glabrous to sparsely pubescent above (or densely pubescent along the midvein), sparsely to densely pubescent below, losing some pubescence with age; apex usually acute or acuminate (sometimes abruptly so), less often rounded; base cuneate, acute, or acuminate; petiole channeled, densely pubescent, 3-12 mm long, 1-2 mm thick; midvein impressed for entire length or only proximally above, prominent below; lateral veins indistinct or up to ca. 30 pairs moderately prominent below; marginal veins equalling laterals or less prominent; blades coriaceous to membranous, dull light grey-green or yellow-green to dark grey-green above (often tinged with reddish-brown when dry), about the same color or a lighter shade below; peduncles uniflorous, 0.5-2.5(-4.5) cm long, 1-2 mm wide, rarely lacking, densely pubescent, often slightly sulcate, solitary or up to 4 in a row in the leaf axils; bracteoles ovate to lanceolate, 1.5-8 mm long, 0.9-4 mm wide, 1.3-5.5 times as long as wide, coriaceous to subcoriaceous, densely pubescent without, densely pubescent to sparsely pubescent within, usually clasping the hypanthium, persistent until the fruit matures or sometimes deciduous before the fruit matures in var. acrophylla; Calyx-lobes ovate to triangular, concave throughout entire inner surface, valvate or overlapping along the narrow, membranous margins of two lobes, otherwise coriaceous, tightly closed in the bud, 2.5-6.5 mm long, 2-6 mm wide, 0.8-1.7 times as long as wide, densely pubescent to glabrous without and within; hypanthium obconic, densely pubescent, 2-5 mm long; disk 2.5-6 mm across, sparsely to densely pubescent; style 5-10 mm long, sparsely pubescent to glabrous; stamens 130 to over 500, 5-17 mm long; anthers 0.4-0.6 mm long when dry; petals more or less orbicular, less often clawed, 2.5-7.5 mm in diam., sparsely pubescent to glabrous within, densely pubescent to glabrous without, the margin sometimes irregular; ovary 3-4-locular; ovules (5-)7-14 per locule; fruit purple black to grey, 1-1.5 cm in diam., puberulent to pubescent; seeds about 3-5, oblong, 0.6-1 mm long.

  • Discussion

    The two varieties of Myrceugenia mycioides are undoubtedly closely related and together form a logical taxonomic unit. It is usually possible to separate them using calyx-lobe length and the presence or absence of dense pubescence within the calyx-lobes. Leaf size, hair size and hair color are usually correlated with these characteristics of the calyx-lobes. But because division is often difficult, especially in the northern part of their range, and because the two entities form a natural unit, they have been retained as one species.

    When one compares the flowering periods of the two varieties, it is apparent that they reach maxima at slightly different times of year, Myrceugenia myrcioides var. acrophylla from January to March, and M. myrcioides var. myrcioides in April and May. In the table below are shown all the phenological data for the flowering specimens available to me, except for my own collections made in October through December, which would have skewed the results towards the months in which I collected. There were a total of 43 collections of M. myrcioides var. acrophylla and 33 of M. myrcioides var. myrcioides.

    [table]

    The differences in flowering periods are probably more pronounced than is indicated in the table because collectors generally do not collect in proportion to the number of flowering individuals encountered. Whether the difference in flowering period is an adaptation for maintaining reproductive isolation or caused by some other factor is an interesting problem. The two varieties have nearly the same range and often grow near one another. Assuming that they are adapted to somewhat different niches, and that they are still capable of interbreeding, then it would be to their mutual advantage to have different flowering periods.

    The fruits of both varieties seem to mature mainly in the late winter and spring months from July to November. It is not obvious to me what ecological differences there are between them. They both grow in the planalto and in the coastal lowlands. Distribution maps of both varieties are shown in Fig. 19.