Cressa (genus)

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Cressa
Cressa truxillensis, habitus

Cressa truxillensis , habitus

Systematics
Nuclear eudicotyledons
Asterids
Euasterids I
Order : Nightshade (Solanales)
Family : Bindweed family (Convolvulaceae)
Genre : Cressa
Scientific name
Cressa
L.

The Cressa are a plant kind from the family of wind plants (Convolvulvaceae). The only four species occur in both the Old and New World as well as Australia .

description

Cressa cretica
Cressa truxillensis leaves and flowers

Cressa species are multi - branched subshrubs that reach heights of about 20 centimeters. They are hairy with tight-fitting, curly trichomes . The foliage leaves are covered with petioles 0.5 to 2 mm long , the leaf blades are 5 to 11 mm long, (rarely only 1 to) 3 to 5 mm wide, elliptically elongated, pointed at the front and wedge-shaped and also closely haired at the base .

The flowers stand individually in the axils and form terminal groups. The inflorescence stalks are 1 to 2 mm long; the prophylls are unevenly shaped, about 3 to 4 mm long and 1 mm wide; Flower stalks are missing. The sepals are roughly the same size, inverted ovoid and blunt in front, the outer ones are 3 to 4 mm long and 2 mm wide and hairy, the inner ones are 3 to 3.5 mm long and 1 mm wide. The crown is white or pink in shape, plate-shaped and 5.5 to 6 mm long. The corolla tube is 3.5 to 4 mm long, the coronet is covered with five blunt, externally hairy corolla lobes, which are shorter than the corolla tube.

The stamens are above the crown, are 2.5 to 3 mm long and hairless, the anthers are 1.3 to 1.5 mm long and elongated. The two-chamber ovary is occupied rauhaarig egg-shaped and at the top. It has two styluses of unequal length, about 2.5 to 3 mm in length, which in turn have smooth, head-shaped scars .

The fruit is a 4 to 5 mm long and 3 mm wide, egg-shaped, brown, unicameral capsule , which is surrounded at least at the base by the permanent calyx. The tip is hairy to velvety. Usually the fruit contains only a single seed , this is egg-shaped, 3 to 3.5 mm long, brown to dark brown, smooth and hairless.

Locations

All Cressa species are salt plants (halophytes) and are adapted to life on a variety of soil types , such as alkaline soils, lava , clay or sand .

Systematics and distribution

Two of the species of the genus occur exclusively in the New World , another in Europe , Africa , Middle East and South Asia , as well as Madagascar . The fourth type of the genus is limited to Timor and Australia .

Botanical history

The genus Cressa was first described by Carl von Linné in 1753 with Cressa cretica as the only species . The botanical genus name Cressa is derived from kris or kriti , which means something like "from Crete". There is probably no etymological connection to cress. As a result, the species concept varied greatly within the genus, so that on the one hand all forms within the genus were incorporated into the type species Cressa cretica or on the other hand up to 19 individual species, some of which only show minor morphological and biogeographical differences, were described. However, many authors recognize two types in the Old World and one or two types in the New World and Australia. However, many authors who unite the New World and Australian representatives in one species note that morphological differences between the two groups can also be found here. Daniel Frank Austin therefore recognizes a total of four species in his revision of the genus Cressa from 2000.

External system

Within the bindweed family, the genus Cressa is classified according to molecular biological knowledge in the tribe Cresseae , of which it is a type genus.

Internal system

The genus Cressa contains only four species:

  • Cressa australis R.Br. (Syn .: Cressa cretica var. Australis (R.Br.) Choisy , Carpentia floribunda Ewart & OBDavies ): It iswidespreadin Australia and occurs on Timor .
  • Cressa cretica L. (Syn .: Cressa ballii Batt. , Cressa cretica var. Indica (Retz.) Choisy , Cressa cretica var. Salina J.A. Schmidt , Cressa cretica var. Villosa (Hoffmanns. & Link) Choisy , Cressa humifusa Lam. , Cressa indica Retz. , Cressa intermedia T.Anderson , Cressa loscosii Trémols , Cressa microphylla St.-Lag. , Cressa monosperma Stokes nom. Superfl., Cressa villosa Hoffmanns. & Link ): The wide distribution area extends from the Mediterranean and Africa to Western Asia , Central Asia and the Indian subcontinent .
  • Cressa nudicaulis Griseb. (Syn .: Cressa aphylla A.Heller ): It occurs in southeast Texas , in the Mexican state of Tamaulipas and in northern Argentina .
  • Cressa truxillensis Kunth (Syn .: Cressa arenaria Willd. Ex Schult. , Cressa australis var. Petiolata Meisn. , Cressa cretica var. Truxillensis (Kunth) Choisy , Cressa depressa goodd. , Cressa erecta Rydb. , Cressa insularis House , Cressa minima A .Heller , Cressa multiflora Willd. Ex Schult. , Cressa vallicola A.Heller ): There are no more subtaxa. It iswidespreadin the Neotropics from the western and central USA via Mexico to southern South America.

literature

Web links

Commons : Cressa  - collection of images, videos and audio files

Individual evidence

Most of the information in this article has been taken from the sources given under literature; the following sources are also cited:

  1. ↑ Carl von Linné: Species plantarum: exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas. 1st edition, Lars Salvius, Stockholm, 1753. p. 223 ( botanicus.org ).
  2. ↑ Saša Stefanović, Daniel Austin, Robert Olmstead: Classification of Convolvulaceae: A Phylogenetic Approach In: Systematic Botany , Volume 28, Number 4, 2003. pp. 791-806 ( depts.washington.edu PDF; 318 kB).
  3. ↑ a b c d e Rafaël Govaerts (Ed.): Cressa. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved February 13, 2015.