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Corolla Tube (corolla + tube)

Distribution by Scientific Domains

Life Sciences	100%

Selected Abstracts

Morphological variation in relation to flower use in bumblebees

ENTOMOLOGICAL SCIENCE, Issue 2 2006
Maki N. INOUE
Abstract To understand resource partitioning in a bumblebee community, we analyzed various morphological characters. A total of 1269 individuals of six bumblebee species, Bombus ardens, B. hypocrita, B. diversus, B. ignitus, B. honshuensis and B. beaticola, were examined and principal component analysis showed that the bumblebee species were clearly differentiated. Glossa, prementa and head lengths were positively correlated with the second component, and a longer proboscis was associated with a narrower body, which may help bees to intrude into and access deep-lying nectar sources. Bombus diversus, with a long proboscis and narrow body, preferred flowers with a long corolla tube, whereas B. hypocrita and B. ignitus, which have short proboscises and wide bodies, visited flowers with short corollas or dish-shaped flowers. Two pairs of consubgeneric species that have similar morphological characteristics, B. ardens and B. beaticola, and B. hypocrita and B. ignitus, divided flower resources by habitat selection and seasonal partitioning. For resource partitioning among bumblebee species, not only morphology but also other factors, such as habitat and seasonal preference, flower use, foraging behavior, and interspecific interactions, are responsible. [source]

Pollination in Jacaranda rugosa (Bignoniaceae): euglossine pollinators, nectar robbers and low fruit set

PLANT BIOLOGY, Issue 2 2009
P. Milet-Pinheiro
Abstract Nectar robbers access floral nectar in illegitimate flower visits without, in general, performing a pollination service. Nevertheless, their effect on fruit set can be indirectly positive if the nectar removal causes an incremental increase in the frequency of legitimate flower visits of effective pollinators, especially in obligate outcrossers. We studied pollination and the effect of nectar robbers on the reproductive fitness of Jacaranda rugosa, an endemic shrub of the National Park of Catimbau, in the Caatinga of Pernambuco, Brazil. Xenogamous J. rugosa flowers continuously produced nectar during the day at a rate of 1 ,l·h,1. Female and male Euglossa melanotricha were the main pollinators. Early morning flower visits substantially contributed to fruit set because stigmas with open lobes were almost absent in the afternoon. Ninety-nine per cent of the flowers showed damage caused by nectar robbers. Artificial addition of sugar water prolonged the duration of flower visits of legitimate flower visitors. Removal of nectar, simulating the impact of nectar robbers, resulted in shorter flower visits of euglossine bees. While flower visits of nectar-robbing carpenter bees (Xylocopa frontalis, X. grisescens, X. ordinaria) produced only a longitudinal slit in the corolla tube in the region of the nectar chamber, worker bees of Trigona spinipes damaged the gynoecium in 92% of the flowers. This explains the outstandingly low fruit set (1.5%) of J. rugosa in the National Park of Catimbau. [source]

Identification and characterization of pin and thrum alleles of two genes that co-segregate with the Primula S locus

THE PLANT JOURNAL, Issue 1 2007
Jinhong Li
Summary The study of heteromorphy in Primula over the past 140 years has established the reproductive significance of this breeding system. Plants produce either thrum or pin flowers that demonstrate reciprocal herkogamy. Thrums have short styles and produce large pollen from anthers at the mouth of the flower; pins have long styles and produce small pollen from anthers located within the corolla tube. The control of heteromorphy is orchestrated by the S locus with dominant (S) and recessive (s) alleles that comprise a co-adapted linkage group of genes. Thrum plants are heterozygous (Ss) and pin plants are homozygous (ss). Reciprocal crosses between the two forms are required for fertilization; within-morph crosses are impeded by a sporophytic self-incompatibility system. Rare recombination events within the S locus produce self-fertile homostyles. As a first step towards identifying genes located at the S locus, we used fluorescent differential display to screen for differential gene expression in pin and thrum flowers. Rather than only detecting differentially regulated genes, we identified two S locus linked genes by virtue of allelic variation between pin and thrum transcripts. Analysis of pin and thrum plants together with homostyle recombinant reveals that one gene flanks the locus, whereas the other shows complete linkage. One gene is related to Arabidopsis flower-timing genes Col9 and Col10; the other encodes a small predicted membrane protein of unknown function. Notwithstanding the diallelic behaviour of the Primula S locus, analysis of pin and thrum plants reveal three alleles for each gene: two pin and one thrum. [source]

Amphistemon and Thamnoldenlandia, two new genera of Rubiaceae (Spermacoceae) endemic to Madagascar

BOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2010
INGE GROENINCKX
Amphistemon and Thamnoldenlandia are described as two new genera of Rubiaceae endemic to Madagascar. The two novelties belong to the predominantly herbaceous tribe Spermacoceae. Amphistemon is unique within the tribe in having its stamens inserted at two levels in the corolla tube. The genus includes two species: the subshrub A. humbertii and the geoxylic herb A. rakotonasolianus. Thamnoldenlandia includes only one species, T. ambovombensis, which differs from most other Spermacoceae in being a medium-sized shrub with winged seeds. We present a detailed description of Amphistemon and Thamnoldenlandia, including observations of pollen and seeds. A molecular phylogenetic study based on atpB - rbcL, petD, rps16 and trnL - trnF sequences demonstrates that the two new genera belong to the Hedyotis,Oldenlandia complex of tribe Spermacoceae. Amphistemon and Thamnoldenlandia are sister taxa and share a common ancestor with the Madagascan endemic genus Astiella. A second, but not closely related, Madagascan clade includes the endemic genera Lathraeocarpa and Gomphocalyx and the Afro-Madagascan genus Phylohydrax. This indicates that the Madagascan endemic members of Spermacoceae are the result of at least two independent colonization events, most likely by long-distance dispersal from the African mainland. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163, 447,472. [source]