<Emphasis Type="Italic">Warneckea austro-occidentalis</Emphasis>, a new species from Cameroon and Nigeria,and re-evaluation of <Emphasis Type="Italic">W. fascicularis</Emphasis> var. <Emphasis Type="Italic">mangrovensis</Emphasis> (Melastomataceae-Olisbeoideae)

Summary  Described and illustrated is Warneckea austro-occidentalis R. D. Stone, an endemic of tropical forests in Cameroon’s South West Province and adjacent Nigeria. The name W. mangrovensis (Jacq.-Fél.) R. D. Stone is also proposed at species level for the taxon originally described as W. fascicularis var. mangrovensis Jacq.-Fél. An IUCN (2001) status of endangered is assigned for both W. austro-occidentalis and W. mangrovensis.     

The pollination ecology of buzz-pollinated Rhexia virginica (Melastomataceae)

We examined the function of floral traits associated with buzz pollination through studies of Rhexia virginica (Melastomataceae) in the Muskoka region of Ontario, Canada. Controlled pollinations demonstrated that the species is self-compatible, but dependent on insects for pollen transfer. Bumble bees made 82 and 90% of observed insect visits to R. virginica in 1996 and 1997, respectively, and effectively buzzed flowers. Buzz pollination did not appear to be highly "specialized" since various species of bumble bee were capable of pollination, and pollen transfer efficiency appeared to be relatively low. Experimental manipulations provided little support for the hypothesis that the yellow color of melastome anthers mimics abundant pollen, thereby deceiving pollinators to visit regardless of whether most pollen has been removed. Fruit set averaged 52.6% among populations, owing largely to infrequent pollinator visits and pollen limitation. Flowers of R. virginica were infertile after a single day of anthesis, but petals were subsequently maintained for 1-2 d and stamens underwent a color change from bright yellow to red. Second-day flowers may function to increase floral display size and hence fertility, without a concomitant increase in pollen discounting. Studies of bumble bee foraging behavior and correlates of seed set provided indirect support for this hypothesis.     

Mecranium juddii (Melastomataceae: Miconieae), a new species from the Massif de la Hotte, Haiti

Mecranium juddii is described and illustrated. It is known only from 1650–1700 m elevation in the Ravine du Sud on the northern slopes of Morne Formon in Macaya National Park, Haiti.Mecranium juddii is a member of theM. multiflorum complex and is phenetically most similar toM. revolutum andM. alpestre, which differ fromM. juddii in stem indumentum or leaf size and shape.     

Pentameric ellagitannin oligomers in melastomataceous plants--chemotaxonomic significance

The pantropical plant family Melastomataceae produces characteristic hydrolyzable tannin oligomers. The latter in this family are distinguished from those in other plant families by the fact that the oligomers from dimers to tetramers are composed of two different alternating monomeric units: casuarictin and pterocaryanin C. These oligomers are metabolites that are produced by intermolecular C-O oxidative coupling between the monomers (or their desgalloyl-or des-hexahydroxydiphenoyl derivatives) forming a valoneoyl group as the link between monomers. The chemotaxonomically significant oligomerization pattern of melastomataceous plants provided helpful suggestions for determining the structures of new oligomers (nobotanins Q-T and melastoflorins A-D) isolated from Monochaetum multiflorum, which belongs to this family. Melastoflorins A-D were characterized as pentamers, which are the largest hydrolyzable tannins composed of different monomeric units.     

Ecuadorian novelties in Blakea and Topobea (Melastomataceae)

Three new species of Melastomataceae (Blakeeae) are described:Blakea subpanduriformis, Topobea adscendens, andT. bullata. All are climbers endemic to the montane forests of the eastern slopes of the Andes in southern Ecuador. In this region, 35% of the Ecuadorian species and 41% of the endemic Ecuadorian species of Melastomataceae occur. The discovery of these three new endemic species underlines the diversity of Melastomataceae occurring on the slopes of the Andes in southeastern Ecuador.     

The Demography of Miconia prasina (Melastomataceae) During Secondary Succession in Puerto Rico1

Miconia prasina (Melastomataceae) is an important colonizing species during early stages of secondary succession in Puerto Rico but its abundance declines with increasing stand age. We studied its demography for 2 yr (1995–1997) in three populations across a pasture to forest chronosequence (1‐, 12‐, and 25‐yr old) and in one population in a hurricane‐disturbed older forest (>60‐yr old). Vegetative growth was positive in the two young sites, but negative in the two older sites. The highest percentage of plants that flowered occurred in the two younger sites but highest seed production occurred in the 25‐yr‐old site. Although seed germination occurred in the two older sites, no seedlings established. Vegetative reproduction (root sprouts) was found in all sites, with most sprouts occurring in young sites. The 2 yr of census data were used to construct stage‐based transition matrices. In the two young sites, the average population growth rate was positive (λ > 1), while average population growth was negative in the two older sites (λ < 1). Elasticity, a measure of the effects of proportional changes in life‐history transitions to the long‐term population growth rate, varied across both stages and sites. Elasticity shifted from large plants in young sites to small plants in older sites. Across all sites, elasticities related to survival were more important than those of growth or vegetative reproduction. The demographic analysis supported the previous observations of changes in the density of M. prasina based on the chronosequence and also suggests that establishment via seeds must occur prior to abandonment in active pastures.