Gibsoniothamnus

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Gibsoniothamnus
Systematics
Nuclear eudicotyledons
Asterids
Euasterids I
Order : Mint family (Lamiales)
Family : Schlegeliaceae
Genre : Gibsoniothamnus
Scientific name
Gibsoniothamnus
LOWilliams

Gibsoniothamnus is a genus of plants that is classified in the Schlegeliaceae family , which comprises only four genera. The eleven to twelve species are distributed in the Neotropics from Mexico via Central America to northern Colombia , where they mostly thrive in mountain rainforests .

description

Vegetative characteristics

Gibsoniothamnus species are mostly strongly branched shrubs that occasionally grow climbing or crawling, only Gibsoniothamnus allenii and Gibsoniothamnus mirificus have found small trees with heights of up to 5 meters. In almost all cases the plant specimens grow epiphytically , only rarely do individuals grow on the ground. The young twigs are stalk-round, or edged or winged due to the cork-like extensions of the raised leaf bases. The bark is hairy or balding. With age they develop a light gray bark , which is often broken up by white, corky lenticels . The stem axes each end in a terminal inflorescence, the branches arise below the inflorescence from the leaf axils.

The opposite or nearly opposite permanently arranged on the branches leaves are divided into petiole and leaf blade. Leaves facing each other at a node are of the same shape, but of different sizes. The leaf stalks are relatively short. The leaf blades are always simple and have entire margins. Often the leaf edges are slightly bent back. The leaf blades are almost leathery in most species, especially in the species Gibsoniothamnus truncatus , Gibsoniothamnus grandiflorus and Gibsoniothamnus latidentatus they are thick and firm. The leaf veins are sunken on the upper side and protrude on the lower side. In many cases the leaf blades are elliptical, often dotted with glands, and domatia are found on the underside of the axils between the main vein and the secondary veins .

Inflorescences and flowers

The inflorescences are zymous , but can be greatly reduced, so that in some species they only consist of a single flower. The flowers are often in clusters on long pedicels , the upper areas of which are often significantly thickened directly below the calyx , and which are accompanied by bracts .

The hermaphrodite flowers are zygomorphic with a double flower envelope . The chalice is bell-shaped and often colored in bright purple or red tones. It looks lobed, but the lobes arise as five lateral outgrowths with upwardly directed appendages. The five petals are tubular to narrow funnel-shaped and depending on the slightly zygomorphic to radial symmetry. Their color is usually bright purple to pink, magenta or red, only rarely white. The five rounded, uneven corolla lobes are significantly shorter than the corolla tube.

The four fertile stamens are of the same shape or occur in two slightly different pairs. They stand free from each other and do not protrude beyond the crown. They are fused with the corolla tube above the corolla tube base. The stamens are thread-like and bent near the top. The two separate anthers are connected by a wide connector. In addition to the fertile stamens, a sterile staminodium is formed, which is usually shorter than the fertile stamens. A flower base is missing. Two carpels are a zweifächrigen ovary connate of a number of ovules includes. The elongated stylus is longer than the stamens and ends in a little head-shaped scar .

Fruits and seeds

The durable calyx is present on the fruit and is often enlarged. The spherical to almost spherical berry is pale green, white or pale pink in color when ripe. In contrast to the fruits of the closely related genus Schlegelia , however, it does not have a hard outer shell. The fruit contains a wide variety of seeds. The seeds are spindle-shaped. The seed coat is net-like, the edge and the ribs of the net on the seed coat are often frayed or covered with long hair. There is no endosperm in mature seeds , the embryo is straight.

ecology

As pollinators of Gibsoniothamnus are birds and insects believed the species likely with larger flowers on pollination by birds ( ornithophily ), the species with smaller flowers on pollination by insects ( Entomophilie adapted). It has been observed that the fruits of Gibsoniothamnus alatus are eaten by parrots , so that it can be concluded that the seeds have spread by birds ( zoochory ).

Locations

The locations are mostly in low mountain rainforests at altitudes of 500 to 1500 meters. Only the Panamanian species Gibsoniothamnus grandifolius and Gibsoniothamnus versicolor occur below 500 meters and Gibsoniothamnus allenii can be found at altitudes of up to 3000 meters.

Systematics, botanical history and distribution

Botanical history

The genus Gibsoniothamnus was 1970 Louis Otho Williams set up . The genus name Gibsoniothamnus honors the American botanist Dorothy L. Nash Gibson born. Nash (1921–2012), who made Williams aware of the previously misassigned species. Williams assigned her to three species that were previously included in the genus Clerodendron . He sees Gibsoniothamnus as closely related to the genus Schlegelia and classifies both genera in the area between the families of Scrophulariaceae and Bignoniaceae, which was not yet fully understood at the time .

The species described by Paul Carpenter Standley and Julian Alfred Steyermark in 1940 as Clerodendrum pithecobium was named Gibsoniothamnus pithecobius by Williams when the genus was first described. However, he overlooked the fact that this species with the name Schlegelia cornuta already had a name given by John Donnell Smith in 1893 . In 1971, Alwyn Gentry introduced the name Gibsoniothamnus cornutus for the species. The species Clerodendron epiphyticum , initially explicitly not included in this genus by Williams in the first description, was assigned to the genus as Gibsoniothamnus epiphyticus in 1972 , after he received another specimen for investigation, which better represented the characteristics of the flowers. Further species were described by Alwyn Gentry from 1974, after his unexpected death in 1993, Kerry Barringer continued the joint work he had already started and published further initial descriptions from 1995. In 2004 a revision of the entire genus Gibsoniothamnus was published by Kerry Barringer . The species Gibsoniothamnus ficticius , also described by J. Francisco Morales in 2004, is based on a herbarium specimen which Barringer assigned to the species Gibsoniothamnus epiphyticus in his revision .

The genus Gibsoniothamnus has been dealt with by different authors in several flora works : 1973 in the "Flora of Guatemala" by Louis Otho Williams, 1979 in the "Flora of Panama" by William D'Arcy and 2000 in the "Flora Costaricensis" by William Burger and Kerry Barringer .

External system

The genus Gibsoniothamnus together with the genera Schlegelia , exarata and Synapsis family schlegeliaceae . With the other genera of the family, Gibsoniothamnus has the woody stem axis , entire leaves, symmetrical petals and zygomorphic flowers, four fertile stamens, an ovary made up of two carpels and non-leaping, fleshy fruits. The phylogenetic relationships between the species have not yet been investigated (as of 2004).

Species and their distribution

The range of Gibsoniothamnus species extends from southern Mexico across Central America to the borders of Panama and Colombia . However, no representatives were found in Honduras , El Salvador and Nicaragua . The northernmost and westernmost distribution has Gibsoniothamnus cornutus ; this species occurs as far as the Sierra Santa Marta in the south of the Mexican state of Veracruz . Gibsoniothamnus alatus has the easternmost and southernmost occurrences in the Cerro Tacaruna on the border between Panama and Colombia.

The genus Gibsoniothamnus contains eleven to twelve species:

The species can be roughly divided into two groups based on the size and shape of the flowers. However, these features are often highly variable, so that a reliable division cannot be made. The species, which have quite large, red colored and funnel-shaped flowers, also tend to develop larger inflorescences and have larger and thicker leaves. Its branches are still more broadly winged or more angled than those of the species with smaller, magenta-colored and tubular flowers.

literature

Individual evidence

  1. ↑ a b c d e f g h i Kerry Barringer: A Revision of Gibsoniothamnus LOWilliams (Schlegeliaceae). In: Brittonia. Volume 56, Number 3, 2004, pp. 213-237. doi : 10.1663 / 0007-196X (2004) 056 [0213: AROGLO] 2.0.CO; 2
  2. ↑ Lotte Burkhardt: Directory of eponymous plant names. Extended Edition. Botanic Garden and Botanical Museum Berlin, Free University Berlin Berlin 2018. ( bgbm.org ).
  3. ↑ Louis O. Williams: An Overlooked Genus of the Scrophulariaceae. In: Fieldiana Botany. Volume 32, Number 14, 1970, pp. 211-214.
  4. ↑ Alwyn H. Gentry: Note On Gibsoniothamnus. In: Fieldiana Botany. Volume 34, Number 5, 1971. p. 55.
  5. ↑ Louis O. Williams: Tropical American Plants, XII. In: Fieldiana Botany. Volume 34, Number 8, 1972, pp. 101-132.
  6. ^ Alwyn H. Gentry: Gibsoniothamnus (Scrophulariaceae) in Panama. In: Annals of the Missouri Botanical Garden. Volume 61, Number 2, 1974, pp. 533-537.
  7. ↑ Kerry Barringer, Alwyn Gentry: New Species of Gibsoniothamnus (Bignoniaceae: Schlegelieae). In: Novon. Volume 5, Number 2, Summer 1995, pp. 120-124.
  8. ↑ J. Francisco Morales: Sinopsis del género Gibsoniothamnus (schlegeliaceae) in Costa Rica, con una nueva especie . In: Lankesteriana. Volume 4, Number 1, 2004, pp. 1-4.
  9. ^ Paul C. Standley, Louis O. Williams: Scrophulariaceae. In: Paul C. Standley, Louis O. Williams, Dorothy N. Gibson (Eds.): Flora of Guatemala. Fieldiana Botany, Volume 24, Part IX, Number 4, 1973, pp. 319-416.
  10. ^ William G. D'Arcy: Scrophulariaceae. In: Robert E. Woodson, Jr., Robert W. Schery (Eds.): Flora of Panama. In: Annals of the Missouri Botanical Garden , Volume 66, 1979, pp. 173-272.
  11. ^ William Burger and Kerry Barringer: Schlegeliaceae. In: William Burger (Ed.): Flora Costaricensis. In: Fieldiana Botany, New Series. Number 41, 2000, pp. 69-77.
  12. ↑ a b c d e f g h i j k l m Rafaël Govaerts, 2003: World Checklist of Seed Plants Database in ACCESS G , 1-40325, Rafaël Govaerts (ed.): Gibsoniothamnus. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved June 5, 2020.

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This version was added to the list of articles worth reading on February 10, 2010 .