oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Distribution and abundance of the edible orchids of the southern highlands of Tanzania
AMS Nyomora
Tanzania Journal of Science , 2005,
Abstract: All orchids have showy flowers and many are therefore popular as exotic houseplants as well as contributing significantly to eco-tourism. A special attribute of some orchid genera is the production of edible tubers, an attribute that can contradict eco-tourism if harvesting is not done sustainably. Such is the case in the Southern Highlands where for example, Kitulo Plateau has been gazetted to be a National Park but where edible orchid harvesting is a serious conservation problem. Botanically, unsustainable harvesting can mean the loss of important germplasm even before some species are known to exist. A field survey was undertaken for three weeks in March 2002 in the Southern Regions of Tanzania (Iringa, Mbeya, Rukwa and Ruvuma) to study aspects of the extent of the distribution, diversity and density of edible orchids. Tools for identification included structured questionnaire, on-the-spot identification as well as using herbarium voucher samples and keys. Analytical tools included Shannons' diversity index and Canonical Community Ordination (CANOCO) and ANOVA in Microsoft Excel. A total of 13 edible species of orchids were documented during the survey all of them from the genera Habenaria, Disa and Satyrium. While Tandala and Molo hills had the highest species Diversity Index (over 1.2), Kitulo Plateau showed the greatest species density of over 200/30m2 quadrants. Local communities in Madaba in Ruvuma, Molo, and Mbisi in Rukwa regions used the orchids as vegetables and snacks in lieu of animal meat. The rest of the studied areas used orchids as a source of cash by selling to Zambian traders and or to their middlemen. More research is needed to monitor growth phases, reproductive/propagation studies as well as taxonomic and systematic studies preferably using molecular techniques to determine relationships amongst edible orchids and their non edible relatives. Tanzania Journal of Science Vol. 31 (1) 2005: pp. 45-54
Epiphytic orchids of Nepal  [PDF]
M Ghimire
Banko Janakari , 2008, DOI: 10.3126/banko.v18i2.2173
Abstract: This paper includes a list of 207 species of epiphytic orchids from Nepal that belong to 49 genera including 5 endemic species (Bulbophyllum ambrosia, Eria baniai, E. nepalensis, Oberonia nepalensis and Pleione coronaria). Phytogeographical distribution along with altitudinal ranges of all of these epiphytic species, phenology of flowering of 199 species and host plant(s) of 148 species have been reported herewith. The aim of this paper is to assess the distribution patterns, host-epiphyte relationship and phenology of flowering of Nepalese epiphytic orchids.
Medicinal Orchids of Nepal: Are They Well Protected?  [PDF]
K.P. Acharya,M.B. Rokaya
Our Nature , 2010, DOI: 10.3126/on.v8i1.4315
Abstract: This paper aims to explore distribution pattern of orchids used for medicinal purpose and their conservation aspect. We compiled information on 82 species of orchids which are used as herbal medicine. Maximum richness of medicinal orchids was observed at an elevation of 1700 msl but, the maximum numbers of protected areas are located at an elevation of 3000 to 3500 msl. There is a negative correlation between number of protected areas and medicinal orchid species richness mentioning that the protected areas are less synchronized with medicinal orchids of Nepal. DOI: 10.3126/on.v8i1.4315
Native Orchids of Oklahoma
Magrath, Lawrence
Oklahoma Native Plant Record , 2001,
Abstract: As of the publication of this paper Oklahoma is known to have orchids of 33 species in 18 genera, which compares to 20 species and 11 genera reported by Waterfall (1969). Four of the 33 species are possibly extinct in the state based on current survey work. The greatest concentration of orchid species is in the southeastern corner of the state (Atoka, Bryan, Choctaw, LeFlore, McCurtain and Pushmataha counties).
Orchids diversity of Situ Gunung, Sukabumi  [PDF]
NINA RATNA DJUITA,SRI SUDARMIYATI,HENDRIUS CANDRA,SARIFAH
Biodiversitas , 2004,
Abstract: Study on the orchids diversity was conducted in Situ Gunung, sub district of Kadudampit, district of Sukabumi, West Java. There were 41 collection numbers, consist of 18 terrestrial orchids, 22 epiphyte orchids, and one saprophyte orchid, belong to 26 genera and 41 species. There were eight species of flowering orchids and the rest were not at flowering stage. Agrostophyllum bicuspidatum J.J.Sm, Plocoglottis acuminata Bl dan Appendicula sp. were commonly found at Situ Gunung. Species orchid of Calanthe triplicata (Willemet) Ames and Plocoglottis acuminata Bl found in a clumped group. Tainia elongata J.J. Sm was the only endemic orchid in Java from this situ.
A Study of the Epiphytic Orchids in Jobolarangan Forest  [PDF]
MARSUSI,CAHYANTO MUKTI,YUDI SETIAWAN,SITI KHOLIDAH
Biodiversitas , 2001,
Abstract: The objective of the research was to know the species of epiphytic orchids in Jobolarangan forest. The orchid samples were taken from all stand-plants. The plants were chosen randomly by considering the diversity and richness of orchids that attach on it. Each plant was sampled in three repetitions. Sampling of orchids existence in the plant’s stand were done using transect method through a zonation system. In this research 11 epiphytic-orchids such as Bulbophyllum bakhuizenii Stenn, Coelogyne miniata Lindl, Coelogyne rochussenii de Vr., Dendrobium bigibbum Lindl., Dendrobchilum longifolium, Eria bogoriensis, J.J.S. Liparis caespitosa (Thou.) Lindl., Liparis pallida (Bl.). Pholidota globosa (Bl.) Lindl., Polystachya flavescens (Bl.) J.J.S., and Trichoglottis sp. were found. The host plant stand that was attached with most orchids was Schefflera fastigiata and Saurauia bracteosa, generally in zone three.
Pollinator-Driven Speciation in Sexually Deceptive Orchids  [PDF]
Shuqing Xu,Philipp M. Schlüter,Florian P. Schiestl
International Journal of Ecology , 2012, DOI: 10.1155/2012/285081
Abstract: Pollinator-mediated selection has been suggested to play a major role for the origin and maintenance of the species diversity in orchids. Sexually deceptive orchids are one of the prime examples for rapid, pollinator-mediated plant radiations, with many species showing little genetic differentiation, lack of postzygotic barriers, but strong prezygotic reproductive isolation. These orchids mimic mating signals of female insects and employ male insects as pollinators. This kind of sexual mimicry leads to highly specialised pollination and provides a good system for investigating the process of pollinator-driven speciation. Here, we summarise the knowledge of key processes of speciation in this group of orchids and conduct a meta-analysis on traits that contribute to species differentiation, and thus potentially to speciation. Our study suggests that pollinator shift through changes in floral scent is predominant among closely related species in sexually deceptive orchids. Such shifts can provide a mechanism for pollinator-driven speciation in plants, if the resulting floral isolation is strong. Furthermore, changes in floral scent in these orchids are likely controlled by few genes. Together these factors suggest speciation in sexually deceptive orchids may happen rapidly and even in sympatry, which may explain the remarkable species diversity observed in this plant group.
Determination of the power law exponent for southern highlands of Tanzania
HH Mwanyika, RM Kainkwa
Tanzania Journal of Science , 2006,
Abstract: The 1/7th power law is among the methods that have been used to extrapolate wind speed to the hub heights of wind turbines from the measuring levels. However, it tends to underestimate the actual long-term average wind speeds. In this paper, the power law exponent for Makambako, a site located in the southern highland zone of Tanzania, was established using wind speeds measured at heights Z1=2 m and Z2=7 m. The average power law exponent obtained at the test site was 0.47, a value that is substantially higher than the 1/7th power law exponent. It is low during the dry season and high during the rainy season. Values of the exponent higher than the overall mean were observed during the night while lower values were detected during the daytime. The overall mean value of the exponent determined from this trial site can be used to project wind speed to desired heights in areas with similar topographical features especially those in the southern highlands of Tanzania, in which the experimental site is situated. Tanzania Journal of Science Vol. 32 (1) 2006: pp. 103-108
The vegitation of the Golden Gate Highlands National Park  [cached]
B. R. Roberts
Koedoe : African Protected Area Conservation and Science , 1969, DOI: 10.4102/koedoe.v12i1.744
Abstract: The vegitation of the Golden Gate Highlands National Park
Pollinator-Driven Speciation in Sexually Deceptive Orchids  [PDF]
Shuqing Xu,Philipp M. Schlüter,Florian P. Schiestl
International Journal of Ecology , 2012, DOI: 10.1155/2012/285081
Abstract: Pollinator-mediated selection has been suggested to play a major role for the origin and maintenance of the species diversity in orchids. Sexually deceptive orchids are one of the prime examples for rapid, pollinator-mediated plant radiations, with many species showing little genetic differentiation, lack of postzygotic barriers, but strong prezygotic reproductive isolation. These orchids mimic mating signals of female insects and employ male insects as pollinators. This kind of sexual mimicry leads to highly specialised pollination and provides a good system for investigating the process of pollinator-driven speciation. Here, we summarise the knowledge of key processes of speciation in this group of orchids and conduct a meta-analysis on traits that contribute to species differentiation, and thus potentially to speciation. Our study suggests that pollinator shift through changes in floral scent is predominant among closely related species in sexually deceptive orchids. Such shifts can provide a mechanism for pollinator-driven speciation in plants, if the resulting floral isolation is strong. Furthermore, changes in floral scent in these orchids are likely controlled by few genes. Together these factors suggest speciation in sexually deceptive orchids may happen rapidly and even in sympatry, which may explain the remarkable species diversity observed in this plant group. 1. Introduction The species diversity in the orchid family is extraordinary. There are more than 20 000 species in the orchid family [1], representing about 10 percent of angiosperm species. The remarkable floral forms found among orchids have always fascinated botanists and evolutionary biologists. Orchid species richness and the spectacular diversity of plant-pollinator interactions provide an exceptional opportunity for the study of pollinator-driven speciation. There is more and more evidence suggesting that pollinators play a major role in the generation of novel floral forms and the maintenance of species diversity in orchids [2, 3]. Sexually deceptive orchids are particularly suitable for investigating pollinator-driven speciation, because of their specialised pollination system. Here, using sexually deceptive orchids as examples, we systematically review what is known about the process of pollinator-driven speciation, examine the key factors that are essential for speciation processes, and discuss the possible modes of speciation in this orchid pollination system. In particular, we focus on the scenario of ecological speciation with gene flow. Many theoretical analyses have
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.