Thomandersia

Thomandersia is a plant genus of the order of Lippenblütlerartigen ( Laminales ). The genus was named in honor of the Scottish botanist Thomas Anderson. The six distinct species within the genus are found only in parts of central and western Africa.

The position of the genus within the order has long been controversial, mostly they were attributed to the Acanthaceae. However, molecular biological methods support a classification in a monotypic family Thomandersiaceae.

• 4.1 Outer systematics
• 4.2 Internal systematics

Description

Vegetative characteristics

Thomandersia species are slender shrubs, small trees or occasionally lianas that reach a plant height of 0.5 to 15 m. The stem is round in cross section and may be hairy on young plants. The nodes are flattened and have no stipules or articulated connections. The plants do not contain a milky sap.

The simple leaves are opposite or decussate, the opposing leaves occur in more or less different forms. Usually they are clearly stalked, occasionally they are almost sessile. The leaf blades are elongated - elliptical, obovate or occasionally circular or elliptic. The tip is tapered or bulged. The base is wedge-shaped to rounded. The smaller leaves of a pair of leaves are sometimes heart-shaped, more or less coriaceous and irregularly covered with non - translucent glands. Both surfaces are colored differently, on the top, some scattered trichomes are, the bottom may be covered with fine hair especially on the leaf veins. The leaf margin is entire or provided with some blunt teeth, which are then usually near the top. The midrib is sunk to the bottom and protruding on the top, the primary lateral veins are pinnate, and in between are reticulate secondary lateral veins. At the axils between the midrib and the lateral veins are often tufted Domatien to find.

Inflorescences and flowers

The inflorescences are upright, terminal or axillary grapes that are built dense and pyramidal or more or less loosely. The flowers are almost sessile to petiolate irregularly arranged either opposite or in whorls of three petals. The bracts are about 1 mm long, triangular - pfriemförmig and hairy. The bracts are shorter than 1 mm, pfriemförmig, ciliated and stand on the sides of the cup.

The calyx is bell-shaped and filled with five short, triangular lobes. It's green, purple or brown in color and fleshy. The surface may be hairy, the margin is ciliated. He is in the fruits resistant, enlarges and forms at the achsabgewandten page one or two swollen hill each with one or two more or less conspicuous openings. The zygomorphe, bilobed, slightly leathery crown is 10 to 20 mm long and greenish, white, yellow, orange, red, pink or purple colored, often it is provided with darker stripes. The corolla tube may be hairy and is at the achszugewandten side near the base slightly tuberculate. The upper lip is two-lobed, the lower lip is three-lobed and more or less concave or provided with projecting lateral lobes. The tabs themselves are entire or sometimes wavy bounded and glandular hairy.

The four stamens occur in two lengths and are between the Corolla lobe. Do not stand or only slightly above the crown out. The stamens are fused to the corolla tube. They may be hairless, glandular or finely hairy. The dust bags are made of two counters, the stamens put dorsal (back ) on. The anthers open by outwardly facing longitudinal slots. The pollen grains are elliptical - kügelförmig, flattened at the poles and dotted on the surface or five or sechskolpat. In addition to the stamens of a single, pfriemförmiges Staminodium is formed, which is shorter than 1 mm.

The ovary is sessile, upper constant and zweifächerig, the placentation is axial. Each ovary contains two or three compartment surrounded by the placenta ovules. At the base of the ovary is swollen, the fabric is nectar leader, but a flower base is not formed. The ovary is glabrous, glandular- hairy or with accompanying hair, he's wearing a different style, which terminates in a cylindrical or two-lobed stigma.

Fruit and seeds

The fruit is nearly spherical to elliptical, conical or ovoid capsules, which are dry at maturity, woody and brown - black. The walls are up to 1.5 mm thick, they jump along in two flaps.

The seeds are black, brown, orange, yellow or cream colored. Their shape is spherical or oval to elliptical, the diameter is 2 to 5 mm. The seed surface is provided with triangular scales arranged spirally or rounded warts. The seeds have a flattened and elongated extension of the seed shaft ( Funikel ) having a width of up to 2 mm and a length of up to 5 mm.

Dissemination and locations

The species of the genus are widespread in western and central Africa, they come in southeastern Nigeria, southern Cameroon, Gabon, Equatorial Guinea, the Democratic Republic of Congo, the Republic of Congo and the Central African Republic before. Thomandersia anachoreta comes before disjoint from the remaining species of the genus in Liberia and the Ivory Coast.

This distribution areas support the hypothesis of a Guineo -Congo Lischen phytogeographic region. Both between species but also within species are different disjunctions and Endemismuszentren identify. Within the entire genus the Dahomey Gap is also pronounced.

The locations of the species are in the shrub layer of evergreen, some deciduous, mixed, wet or dry forests, gallery forests, along rivers, coasts, flood plains, plains and highlands forests and forest residues. Above all, they are there on the edges of woods to find clearings, disturbed areas and along roads. They grow on loamy, rocky, laterithaltigen, containing small, sandy, calcareous, granite or iron-rich soils.

Ecology

At the sites, the plants are mostly found plenty, occasionally they form dense clusters or thickets, forming adventitious roots at the nodes and re- sprout from severed stumps.

The plants are eaten by various mammalian species, by Bongos (Tragelaphus eurycerus ) and the forest elephant (Loxodonta cyclotis ). Schmimpansen (Pan troglodytes) use branches or young offspring of Thomandersia hensii in order to poke into termite mounds before they seek itself termites.

At the nectaries of the cup ants were observed. At the crowns of Thomandersia hensii punctures that indicate nectar theft are often to be found.

System

Outer systematics

Molecular biological studies have confirmed the classification of the Thomandersia in the order of Lippenblütlerartigen ( Lamiales ), but the species could not be classified into one of the recognized families of the order. The studies suggest that a compound of the genus is the Schlegeliaceae, but for this arrangement could only weak evidence be found.

Inside systematics

Within the genus six types can be distinguished:

• Thomandersia anachoreta Heine
• Thomandersia butayei De Wild.
• Thomandersia congolana De Wild. & T.Durand
• Thomandersia hensii De Wild. & T.Durand
• Thomandersia laurentii De Wild.
• Thomandersia laurifolia T.Anderson ex Benth.

The type species of the genus is Thomandersia laurifolia.

Botanical history

The genus was first described in 1876 by Thomandersia George Bentham under the name Scytanthus. However, since this name was already taken in 1844 by William Jackson Hooker for a genus of the family of milkweed plants ( Asclepiadaceae ), the genus was renamed in 1891 by Henri Ernest Baillon and received it today Thomandersia valid name.

The first description of the genus rewrote only one kind Scytanthus laurifolius ( = Thomandersia laurifolia ), around the turn of the 20th century were described by Émile Auguste Joseph de Wildeman and Théophile Alexis Durand four other species. A sixth species was described in 1966 by Hermann Heino Heine in his revision of the genus.

The taxonomic position of the genus has long been discussed by most authors, the genus was the acanthus ( Acanthaceae ) assigned because the seeds of Thomandersia have the actually occurring only within this family enlarged seed stalks. Based on similar pollen morphology of the genus by some authors but also the sesame plants ( Pedaliaceae ) has been assigned.

Due to the independence of the genus, mainly in the morphology of the leaves and the dust bag, the genus in 1977 by CP was Sreemadhaven described as the only genus of the monotypic family Thomandersiaceae. The confirmed by molecular biological investigations autonomy within the order of Lippenblütlerartigen ( Lamiales ) meant that Alexandra H. Wortley et al. in their revision published in 2007 confirmed its status as a mono- generic family.

Swell

• Alexandra H. Wortley, David J. Harris and Robert W. Scotland: On the Taxonomy and Phylogenetic position of Thomandersia. In: Systematic Botany, Vol 32 (2008), No. 2, pp. 415-444, ISSN 0363-6445, doi: 10.1600/036364407781179716