Rahowardiana
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Rahowardiana is a plant genus of the family of the nightshade family (Solanaceae). It consists of only two species that are native to Panama and Colombia .
description
Vegetative characteristics
Rahowardiana are tall climbing shrubs , the branches of which can reach up to 10 cm in diameter. The leaves stand in threes or four in whorls on very short or 15 to 25 mm long petioles, which show a multitude of transverse crevices. The leaf blade is inverted ovate, has a short, pointed, rounded or slightly notched tip, a blunt or wedge-shaped base, is hairless or only hairy on the underside with simple, three- to five-cell trichomes . They have a size of 15 to 30 × 10 to 21 cm.
Inflorescences and flowers
The inflorescences are reduced to a spherical shape, racemose umbels , which have a total diameter of 10 to 35 cm and stand on a 10 to 40 cm long peduncle and are composed of a large number of flowers .
The flower stalks are hairless and thick, almost stiff and about 5 mm long. Depending on the species, the violet calyx is 3 to 4 or 5 to 6 cm long, inverted conical or almost tube-like in shape and clearly pentagonal. It is longer or only slightly shorter than the corolla tube, five-lobed. The calyx lobes are covered with fine and short glandular or non-glandular hair and are shorter or as long as the calyx tube. The yellow or white crown is zygomorphic , slightly longer than the calyx and, depending on the species, 1.8 to 2 or 6.5 to 7.5 cm long. The five corolla lobes are eyed, unequal in length, wider than long and provided with a rounded tip.
The stamens do not protrude beyond the crown. The hairless stamens are attached in the lower quarter of the corolla tube, at the point of attachment there is an enlargement that is typical for the genus. The anthers are fixed on the back (dorsal), have a linear shape and are 6 to 15 mm long. The back of the anthers is straight, the theca have grown together at the top, the point of origin extends to the lower tip of each theca. The pollen is almost elongated and medium-sized with a diameter of 26 to 35 µm. The pollen grain wall (exine) is about 1.7 µm thick, slightly scaly and has no “Ubisch bodies”.
The two-sheeted ovary each has two chambers, is conically shaped, the Nektarien are slightly wavy. The scar , which does not protrude beyond the crown, is saddle-shaped and grooved in the middle.
Fruits and seeds
The fruits resemble capsule fruits , which are hidden in an enlarging calyx. They are about 20 mm long and 7 mm in diameter, are oblong, conical, beaked, surrounded by a thin, membrane-like pericarp and contain 50 to 60 seeds . These are (2.1) 2.5 to 2.8 mm long, boomerang-shaped, but not concave on the side of the hilum , but straight. The embryo is worm-shaped and only very slightly curved, the cotyledons are elongated and shorter and just as wide as the rest of the embryo. The endosperm is only sparsely developed.
Occurrence
Both species assigned to the genus grow at low altitudes of 800 to 900 m in the rainforests of South America . Rahowardiana wardiana is only known from Panama and Rahowardiana globifera only from Colombia .
Systematics
Only two species have been described within the genus:
- Rahowardiana globifera Knapp & D'Arcy
- Rahowardiana wardiana D'Arcy
The type species is R. wardiana .
Botanical history and etymology
The genus was first described in 1973 by William D'Arcy with the species R. wardiana . It is named after Richard Alden Howard , who was director of the Arnold Arboretum at Harvard University between 1954 and 1978 . In 1993, Sandra Knapp and William D'Arcy described a second species under the name R. globifera .
literature
- Armando T. Hunziker: The Genera of Solanaceae . ARG Gantner Verlag KG, Ruggell, Liechtenstein 2001. ISBN 3-904144-77-4 .
- William G. D'Arcy: Family 170: Solanaceae . In: Robert E. Woodson, Jr., Robert W. Schery (Eds.): Flora of Panama , Part IX, Annals of the Missouri Botanical Garden, Volume 60, Number 3, 1973. Pages 573-780 (first description of the genus and by R. wardiana on pages 670–672)
- Sandra Knapp, William G. D'Arcy: Rahowardiana globifera (Solanaceae), a new Species from Colombia , In: Taxon , Volume 3, 1993. Pages 429-430.