Cressa (genus)
Cressa truxillensis, habitus
The Cressa are a plant genus of the family of wind plants ( Convolvulvaceae ). Your are attributed to four species that occur in both the Old and New World and Australia.
- 6.1 Notes and references
- 6.2 Literature
Description
Cressa are much branched, about 20 cm tall -shrubs. They are hairy with adjacent, striegeligen trichomes. The leaves are bestielt with 0.5 to 2 mm long petioles, the leaf blades are 5-11 mm long (rarely only 1 ) hairy 3 to 5 mm wide, elliptical, elongated, front pointed and wedge-shaped at the base and also fitting striegelig.
The flowers appear singly in the axils and form terminal groups. The inflorescence stems are 1 to 2 mm long; the bracts are unequal shaped, about 3 to 4 mm long and 1 mm wide; Pedicels absent. The sepals are approximately the same size, obovate and blunt front, the outer 3 to 4 mm long and 2 mm wide and hairy, the inner 3 to 3.5 mm long and 1 mm wide. The crown is shaped white or pink, plate- shaped, and 5.5 to 6 mm long. The corolla tube is 3.5 to 4 mm long, the coronary band is busy with five blunt, hairy outside Kronlappen that are shorter than the corolla tube.
The stamens are beyond the crown, are 2.5 to 3 mm long, glabrous, the anthers are 1.3 to 1.5 mm long and elongated. The two-chamber ovary is ovoid and occupied rauhaarig at the top. He wears two unequal length pen of about 2.5 to 3 mm length, which in turn bear smooth, shaped little head scars.
The fruit is a 4 to 5 mm long and 3 mm wide, ovate, brown, unilocular capsule, which is surrounded at least on the basis of UV resistant cup. The tip is rauhaarig hairy to velvety. Usually, the fruit contains a single seed, this is ovoid, 3 to 3.5 mm long, brown to dark brown, smooth and hairless.
Occurrences and locations
Two of the species of the genus are found exclusively in the New World, another in Europe, Africa, Middle and South Asia, as well as in Madagascar. The fourth species of the genus is limited to Timor and Australia.
All representatives are salt plants ( halophytes ) and are to life on a variety of soil types, such as alkaline soil, lava, mud or sand, adjust.
System
Outer systematics
Within the family of wind plants, the genus Cressa are classified by molecular biological findings into Tribe Cresseae, whose type genus it is.
Inside systematics
The representatives of the genus Cressa be divided into four types:
- Cressa australis R.Br.
- Cressa cretica L.
- Cressa nudicaulis Griseb.
- Cressa truxillensis H., B. & K.
Botanical history
The genus Cressa was first described in 1753 by Carolus Linnaeus with Cressa cretica is the only way. As a result, the concept of species within the genus varied greatly, so that on the one hand all forms within the genus in the type species Cressa cretica were incorporated or otherwise up to 19 individual species, which have sometimes only slight morphological and biogeographical differences, have been described. However, many authors recognize two types of the Old World and one or two species in the New World and Australia. Many authors who combine the New World and Australian representatives in a way, but it is recorded that can be observed morphological differences between the two groups here. Daniel Frank Austin therefore recognizes in his revision of the genus from the year 2000 to a total of four types.
Etymology
The botanical genus name is derived from kris or from critical, which means as much as " Crete ". An etymological connection to the cress probably does not exist.