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We describe Blakea ricardoi (Melastomataceae: Blakeeae), a species known only from the Parque Internacional La Amistad in Costa Rica side. It can be distinguished by the long peduncles up to 6.5 cm long, pendant flowers with green petals and indumentum of roughened trichomes. A key to other species of Blakea with pendulous flowers and connivent petals is provided.
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Pterolepis xaxa (Melastomateae, Melastomataceae), a new haplostemonous species from Bahia, Brazil
We describe Pterolepis xaxa (Melastomateae, Melastomataceae), a new species collected in “caatinga rupestre” at Licínio de Almeida, Bahia, Brazil. Pterolepis xaxa resembles the recently described Pterolepis haplostemona, both representing the only two species in the genus that are haplostemonous (i.e., with the stamens equal in number to the petals). Apart from flowers with a single whorl of stamens, P. xaxa can also be recognized by intercalycine projections consisting of a very short central axis topped with 2–3 trichomes, and white petals (vs. intercalycine projections lacking trichomes at the apex and magenta or lilac petals in P. haplostemona).
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- PAR ID:
- 10437440
- Date Published:
- Journal Name:
- Brittonia
- ISSN:
- 0007-196X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Recent field research on the eastern slopes of the Andes resulted in the discovery of a new species ofBomareafrom the Cerro Candelaria Reserve in the Tungurahua province of Ecuador.Bomarea pastazensisis the second smallest species in the genus and differs from the smallest by the presence of glutinous trichomes on the ovary, glabrous sepals, and greenish-yellow petals with purple spots. Based on IUCN guidelines, a preliminary conservation status is assigned as Vulnerable (VU).more » « less
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Miconia tetrandra, a morphologically distinctive species restricted to the Caribbean region, is provided with an updated assessment of its phylogenetic position and taxonomy. A detailed description and nomenclatural treatment are provided, along with a consideration of phenology, distribution and habitat, and citation of specimens examined. The species is a member of the Caribbean clade, and it is unusual within Miconia in having flowers with only four stamens (alternating with the petals), with short, obovate, yellow anthers that each open by two large pores. Miconia tetrandra is morphologically quite divergent from, but is likely related to, a clade comprised by M. angustifolia, M. urbanii, and M. biflora, and these three species traditionally have been included within the genus Tetrazygia. In contrast, M. tetrandra usually has been placed within Miconia.more » « less
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Traits conserved across evolutionary time often provide compelling examples of key adaptations for a given taxonomic group. Tetradynamy is the presence of four long stamens plus two short stamens within a flower and is conserved across most of the roughly 4000 species in the mustard family, Brassicaceae. While this differentiation in stamens is hypothesized to play a role in pollination efficiency, very little is known about the potential function of the two stamen types. The present study sheds new light on this mystery using wild radish (Raphanus raphanistrum), a widespread and well-studied tetradynamous plant. We used data collected from slow-motion videos of pollinators visiting wild radish flowers to test three adaptive hypotheses (not mutually exclusive): (H1) short and long stamens are specialized for either feeding or pollinating; (H2) short and long stamens are specialized for different pollinator taxa; and (H3) the presence of short and long stamens increases pollinator movement and thus effectiveness. We find evidence consistent with hypothesis H3, but no evidence for hypotheses H1 or H2. Thus, tetradynamy may be an adaptation for generalized pollination, enabling effective visits by the variety of pollinators visiting most species of Brassicaceae.more » « less
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Bilaterally symmetric flowers have evolved over a hundred times in angiosperms, yet orthologs of the transcription factors CYCLOIDEA (CYC), RADIALIS (RAD), and DIVARICATA (DIV) are repeatedly implicated in floral symmetry changes. We examined these candidate genes to elucidate the genetic underpinnings of floral symmetry changes in florally diverse Rhododendron, reconstructing gene trees and comparing gene expression across floral organs in representative species with radial and bilateral flower symmetries. Radially symmetric R. taxifolium Merr. and bilaterally symmetric R. beyerinckianum Koord. had four and five CYC orthologs, respectively, from shared tandem duplications. CYC orthologs were expressed in the longer dorsal petals and stamens and highly expressed in R. beyerinckianum pistils, whereas they were either ubiquitously expressed, lost from the genome, or weakly expressed in R. taxifolium. Both species had two RAD and DIV orthologs uniformly expressed across all floral organs. Differences in gene structure and expression of Rhododendron RAD compared to other asterids suggest that these genes may not be regulated by CYC orthologs. Our evidence supports CYC orthologs as the primary regulators of differential organ growth in Rhododendron flowers, while also suggesting certain deviations from the typical asterid gene regulatory network for flower symmetry.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/s12228-023-09747-x
