Pogonieae
| Pogonieae | ||||||||||||
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Pogonia ophioglossoides |
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| Scientific name | ||||||||||||
| Pogonieae | ||||||||||||
| Pfitzer ex Garay & Dunst. |
The tribe pogonieae from the family of orchids (Orchidaceae) contains five genera . The plants are mainly found in South America, some also in North America and East Asia. A notable feature is their hollow stems; In contrast to the related tribe Vanilleae , there are no climbing plants and hardly any mykoheterotrophic plants.
description
Despite the small number of species it contains, the tribe Pogonieae has a fairly wide range of characteristics, especially in the details of the seeds .
The roots are thin and fibrous or form tubers . Velamen either does not exist, is only one cell layer thick, or comprises several cell layers. The shoot is mostly hollow ( Duckeella has massive stems). The leaves are in a basal rosette, or are distributed in two lines on the stem, with Isotria they are in a whorl in the middle of the stem. Some species have no leaves.
The inflorescence is usually terminal - laterally in Duckeella -, little-flowered and unbranched. The flowers are resupinated and often pink or white, sometimes green or brown; yellow at Duckeella . There is a separating fabric between the ovary and the flower cover. The petals are not fused together. Sepals and lateral petals are similar to one another, the lip is usually covered with quills, appendages or hair. The column is slim, the stamen is bent down by more than 90 ° compared to the column axis. The pollen is not stuck together to form pollinia , the pollen grains are present individually (monads) or in groups (tetrads). The seeds have only one seed coat , which loosely envelops the embryo (like most orchids, but in contrast to the closest related tribe Vanilleae ). They are spindle-shaped in Duckeella , Isotria and Pogonia , whereby the seed coat in Pogonia consists of only a few, extremely elongated cells. In Duckeella, there are gaps between the cells of the seed coat. Cleistes has balloon-like seeds with a multicellular seed coat.
The chromosome numbers are 2n = 18, 20 or 24; the chromosomes are relatively large.
distribution
The species of the Tribus Pogonieae are mainly found in South America. The most species-rich genus of the tribe, Cleistes and Duckeella occurs there. In North America, Isotria , Pogonia, and one or two Cleistes species are represented. (The North American Cleistes are also regarded as a separate genus, Cleistesiopsis ). Further Pogonia species can be found in East Asia .
Systematics
The tribe Pogonieae belongs to the subfamily Vanilloideae within the orchid family (Orchidaceae) . Dressler was still unsure about this placement, but recent studies confirm it. The extent of the Pogonieae is essentially the same for different authors, only the little researched genus Pogoniopsis is excluded from the Pogonieae by Pansarin.
Duckeella and possibly Pogoniopsis are the basal genera of the tribe. The remaining tribe is divided into two parts: one clade is made up of the South American Cleistes species, the second the North American and East Asian species. Since the North American Cleistes divaricata and Cleistes bifaria (also viewed by some authors as just one species) are more closely related to the other North American genera than to the South American Cleistes , Pansarin and F. Barros put them in their own genus Cleistesiopsis .
Genera of the tribe Pogonieae:
- Cleistes Rich. ex Lindl.
- Cleistesiopsis Pansarin & F.Barros : It was first published in 2009. It includes three types that are found in the United States.
- Duckeella Porto & Brade
- Isotria Raf.
- Pogonia Juss.
- Pogoniopsis Rchb.f. - so far in Pogonieae, but doubtful. It includes two species found in southeastern Brazil.
supporting documents
- Alec M. Pridgeon, Phillip Cribb, Mark W. Chase, Finn Rasmussen (Eds.): Genera Orchidacearum. Orchidoideae (Part 2). Vanilloideae . tape 3/2 . Oxford University Press, New York and Oxford 2003, ISBN 0-19-850711-9 , pp. 285-286 .
- Robert L. Dressler: Phylogeny and Classification of the Orchid Family . Cambridge University Press, 1993, ISBN 0-521-45058-6 , pp. 108-109 .
- Emerson R. Pansarin, Antonio Salatino, Maria LF Salatino: Phylogeny of South American Pogonieae (Orchidaceae, Vanilloideae) based on sequences of nuclear ribosomal (ITS) and chloroplast (psaB, rbcL, rps16, and trnL-F) DNA, with emphasis on Cleistes and discussion of biogeographic implications . In: Organisms, Diversity & Evolution . tape 8 , 2008, p. 171-181 .
- Kenneth M. Cameron, Mark W. Chase: Phylogenetic Relationships of Pogoniinae (Vanilloideae, Orchidaceae): An Herbaceous Example of the Eastern North America - Eastern Asia Phytogeographic Disjunction . In: Journal of Plant Research . tape 112 , 1999, pp. 317-329 .
Individual evidence
- ↑ a b Rafaël Govaerts (Ed.): Orchidaceae. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved April 1, 2020.
