Meiracyllium
| Meiracyllium | ||||||||||||
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Meiracyllium trinasutum |
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| Scientific name | ||||||||||||
| Meiracyllium | ||||||||||||
| Rchb.f. |
Meiracyllium is a genus of plants within the orchid family (Orchidaceae). The genus includes only two species , which are native to Mexico , Guatemala and El Salvador . They grow epiphytically in dry forests.
description
Meiracyllium are small, herbaceous , perennial plants . They grow with a creeping rhizome that is initially covered by paper-like lower leaves, which fall off over time. The rhizome is constricted at the nodes , its surface is corked. The roots are flexible and flattened in cross section. The velamen that envelops the roots is two to five cell layers thick, and there are no tilosomes . The rhizome merges into the upright stem axis , at the base of which are the renewal buds. The rhizome continues from them in the next growth period, so there is a sympodial growth pattern. Only one leaf is formed per shoot. The succulent leaves are broadly oval, blunt at both ends, sometimes with a small pointed tip at the front. There is no petiole. The color of the leaves is an often reddish green. The bud location is conduplicate, on the upper side there is a longitudinal channel. There are a few hairs ( trichomes ) on both sides of the leaf . Stomata are present on both sides of the leaf, they have four secondary cells.
The inflorescence is a terminal raceme , which is surrounded at the base by some divisive bracts . It contains one to seven flowers that are resupinated and have a pink to purple color. Rare plants with white flowers are known of both species. The paper-like bracts are triangular-oval and pointed. The ovary is curved once or in an S-shape and provided with longitudinal grooves. The petals are not fused together and are similar in shape and dimensions except for the lip . The sepals are oval to lanceolate, often pointing forward, the two lateral ones are somewhat asymmetrical at the base and form a bulge with the base of the lip. The edges of the sepals are curved backwards, while the petals are flat. The lateral petals are narrower than the outer petals, especially at the base. The lip is attached to the column with a broad base , there it forms a bulge directed slightly backwards and encompasses the column with the edges turned upwards. Further in front the column is spread out flat, the edges are slightly wavy, at the front it ends with a point. The column is not curved, it is rounded square in cross section. The stamen does not sit at the end of the column, but dorsally, it is partially covered at the base by a bilobed tissue of the column (clinandrium). The stamen is long-oval in outline, with a heart-shaped base and pointed at the front. It contains eight club-shaped pollinia , two larger and two smaller ones are grouped together, all hanging together on an oval black-brown adhesive disc ( Viscidium ). The scar consists of an obliquely forward-facing surface. The separating tissue between the stigma and the stamen (rostellum) is elongated, ribbon-shaped to long-triangular, at the tip with a small depression in which the viscidium sits. The capsule fruit stands upright, it is oval to spindle-shaped, with six longitudinal keels.
distribution
Meiracyllium is common in Central America in the states of Mexico, Guatemala and El Salvador. It occurs on the side facing the Pacific at altitudes of 450 to 1500 meters. In the north, Meiracyllium gemma grows in the Mexican states from Sinaloa to Oaxaca . Meiracyllium trinasutum occurs further south , which may still reach Honduras. The ranges of the two species are unlikely to overlap.
ecology
The Meiracyllium species are found in dry forests and savannahs, and the climate is characterized by a distinctly dry season. They are less common in more humid forests, such as the mountain rainforests at higher altitudes. The woodlands are often dominated by oaks ( Quercus ) and pines ( Pinus ). Meiracyllium grows epiphytically , sometimes on rocks.
Flowering plants can be found all year round, with Meiracyllium gemma a high point during the rainy season and Meiracyllium trinasutum during the dry season. The flowers give off a cinnamon-like scent, a male of the magnificent bee Euglossa viridissima has been observed with pollinia from Meiracyllium gemma . The fragrance methyl cinnamate indicates pollination by male splendor bees . Related genera that are pollinated by magnificent bees attract them regardless of gender.
Systematics and botanical history
The genus Meiracyllium was established by Heinrich Gustav Reichenbach in 1854 . The name is derived from the Greek μειράκιον meirakyllion , "youth, boy", and refers to the small growth of the plants. The type specimen for the only known species Meiracyllium trinasutum came from Pavón and was given to Reichenbach by Boissier . The exact origin of the plant was unknown to Reichenbach. In 1866 he described a second species, Meiracyllium wendlandii , which he named after Hermann Wendland , who collected the plants and brought them to Europe. A third species description, Meiracyllium gemma , was published by Reichenbach in 1869. The two species Meiracyllium trinasutum and Meiracyllium wendlandii are considered synonymous , so the first published name, Meiracyllium trinasutum , is the valid one.
The relationship of the genus Meiracyllium within the orchids has been assessed differently by different researchers. Reichenbach was unsure about the relationship in view of the incompletely preserved type specimen, but suspected it to be the Vandeae . Bentham and Hooker placed them among the Pleurothallidinae and Schlechter compared them with sophronitis within the Laeliinae . Dressler then set up a separate subtribe Meiracylliinae for the genus, as, in his opinion, it differs too much from the other Laeliinae. However, he considered a close relationship between these two subtrees to be likely, for example because of the similar structure of the Velamen radicum.
First investigations of the DNA showed a placement within the subtribe Laeliinae, whereby the most closely related genera remained unclear. Most likely a position as a sister taxon to a group of Brassavola , Cattleya , Guarianthe and Rhyncholaelia . Due to the large deviations in both the DNA data and the morphology, the result of the cladistic analysis is prone to errors.
The two types are:
- Meiracyllium gemma Rchb.f.
- Meiracyllium trinasutum Rchb.f. (Syn .: Meiracyllium wendlandii Rchb.f. )
Culture
Both species are occasionally cultivated as ornamental plants. They are usually tied to branches, cork or fern roots . Depending on their origin, a high light intensity and a dry rest period must be observed. The hybrid Meiracyllium Trigem ( Meiracyllium trinasutum x Meiracyllium gemma ) with the variety 'Surprise' and the white Meiracyllium trinasutum 'Aida' were awarded by the American Orchid Society .
See also
Individual evidence
- ^ A b c Robert L. Dressler: Phylogeny and Classification of the Orchid Family . Cambridge University Press, 1993, ISBN 0-521-45058-6 , pp. 191 .
- ↑ a b c d e f g h i j Alec M. Pridgeon, Phillip Cribb , Mark W. Chase (eds.): Genera Orchidacearum. Epidendroideae (Part one) . 2nd Edition. tape 4/1 . Oxford University Press, New York and Oxford 2005, ISBN 0-19-850712-7 , pp. 276-279 .
- ↑ a b Eric Hágsater, Miguel Ángel Soto Arenas (ed.): Icones Orchidacearum . Fasc. 5 & 6. Orchids of Mexico. Parts 2 and 3, 2003, ISBN 968-7889-05-5 , pp. 621 .
- ↑ a b c d e Rafaël Govaerts (Ed.): Meiracyllium. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved April 9, 2020.
- ^ A b Heinrich Gustav Reichenbach: Xenia orchidacea: Contributions to the knowledge of the orchids . tape 1 . FA Brockhaus, Leipzig 1858, p. 12 ( botanicus.org ).
- ↑ Cassio van den Berg, Wesley E. Higgins, Robert L. Dressler, W. Mark Whitten, Miguel A. Soto-Arenas, Mark W. Chase: A phylogenetic study of Laeliinae (Orchidaceae) based on combined nuclear and plastid DNA sequences . In: Annals of Botany . tape 104 , 2009, p. 417-430 , doi : 10.1093 / aob / mcp101 .
- ^ Carl L. Withner : The Cattleyas and their relatives . tape 5 . Brassavola, Encyclia and Other genera of México and Central America. Timber Press, Portland, Oregon 1998, ISBN 0-88192-456-3 , pp. 165-168 .
