Plectocephalus

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Plectocephalus
Plectocephalus americanus

Plectocephalus americanus

Systematics
Order : Astern-like (Asterales)
Family : Daisy family (Asteraceae)
Subfamily : Carduoideae
Tribe : Cynareae
Sub tribus : Centaureinae
Genre : Plectocephalus
Scientific name
Plectocephalus
D. Don

The Plectocephalus form a species-poor plant genus in the subfamily of Carduoideae within the family of Compositae (Asteraceae).

description

Illustration of Plectocephalus americanus
Flower head of Plectocephalus chilensis
Population of Plectocephalus chilensis

Vegetative characteristics

Plectocephalus species are annual herbaceous plants that reach heights of 30 to 200 centimeters, depending on the species. In contrast to many genera of the Cynareae tribe , they are not thorny. The upright stems are branched.

The alternate, basal and distributed leaves on the stem are stalked or sessile. The leaf margins are whole or toothed. The leaf surfaces are tomentose and dotted with tiny glands.

Generative characteristics

The cup-shaped inflorescences stand together individually or in openly branched inflorescences. The flower head stems are tubular. The egg-shaped to hemispherical or bell-shaped basket shell has a diameter of 3 to 6 centimeters. The uneven, narrow bracts are arranged in eight to ten rows like roof tiles . The bracts have a whole edge and tips with the fringed appendages that give them their name. The basket bottom is flat. The chaff leaves are bristly.

The flower heads contain many flowers . As with the other Carduoideae, in contrast to the other subfamilies, only tubular flowers are present. The tubular florets at the edge are asexual, sterile , more or less zygomorphic and enlarged, they are pink to purple in color. The inner tubular flowers are fertile and radial symmetry or zygomorphic with very slender and long corolla tubes ; they are pink or purple in color, cream to light yellow. The anthers are tailed and have appendages.

The obovate or barrel-shaped achenes are more or less compressed and have a small elaiosome on one side. The pappus , which falls off early, consists of one to three rows of short bristles with tiny beards.

Systematics and distribution

The genus Plectocephalus belongs to the subtribe Centaureinae from the tribe Cynareae in the subfamily of the Carduoideae within the family of the Asteraceae . Plectocephalus is part of a basal group in the Centaureinae and is not closely related to Centaurea in the narrow sense.

The species from the New World of the Centaurea L. sect. Plectocephalus (D.Don) DC. were separated from the genus Centaurea L. and forms the reactivated genus Plectocephalus D.Don . The genus name Plectocephalus was published by David Don in Robert Sweet : The British Flower Garden , Series 2, 1, plate 51 as early as 1830 . De Candolle then put these species as a section in the genus Centaurea . The botanical genus name Plectocephalus is made up of the Greek words plektos for "woven" and cephale for "head" and refers to the intertwined fringes of the bracts. The genus Plectocephalus only contains species originally from North and South America.

The species that are widespread in Europe, the Mediterranean and Western Asia remain in the genus Centaurea . In plectocephalus there is only one set of chromosomes of x = 13, whereas in Centaurea there is x = 8, 9, 10, 11, 12, 13 or 15. Morphologically , the plectocephalus differ only slightly from the derived and diverse Centaurea .

At least the two species native to the United States and Mexico are used as ornamental plants and have become feral in some areas.

Two to four species belong to the genus Plectocephalus :

swell

  • David J. Keil: Plectocephalus. In: Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico . Volume 19: Magnoliophyta: Asteridae, part 6: Asteraceae, part 1 (Mutisieae – Anthemideae). Oxford University Press, New York / Oxford a. a. 2006, ISBN 0-19-530563-9 , pp. 175 (English). (English)

Individual evidence

  1. ↑ Alfonso Susanna, Nuria Garcia Jacas, Douglas E. Soltis, Pamela S. Soltis: Phylogenetic relationships in tribe Cardueae (Asteraceae) based on ITS sequences. In: American Journal of Botany. Volume 82, No. 8, 1995, pp. 1056-1068, doi: 10.2307 / 2446236 .
  2. ^ The relatives of the Centaurea occurring in North America , 2006 by Jörg Ochsmann: Scientifically oriented page about Centaurea and its relatives.

Web links

Commons : Plectocephalus  - Collection of images, videos and audio files
  • Plectocephalus in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland.