Petalonyx
| Petalonyx | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Petalonyx thurberi |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Petalonyx | ||||||||||||
| A.Gray |
Petalonyx is a plant kind from the family of loasaceae (Loasaceae) and the only representative of the subfamily of Petalonychoidae. It contains five species that are native to northern Mexico and the southwestern United States.
description
Petalonyx are shrubs or subshrubs that usually grow from a thickened, perennial rootstock, the bark often has thick layers of cork. Nettle hair is missing. The leaves are alternate and have short, branched bristles.
The inflorescences are terminal clusters. In front of the upright, five-fold individual flowers are two bracts , the flowers grow axially from a bract .
The often nailed, white petals are free to the base and have a clearly visible midrib . The five stamens are episepal (i.e. in front of the sepals), occasionally offset by the apparently overgrown corolla structure on the outside of the corolla or on the always thread-like stamens enclosed by the edges of the corolla.
The ovary has a hanging ovule on. The fruit is an irregular pentagonal capsule that remains connected to the bract and the two pre-leaves , but the sepals are obsolete.
The number of chromosomes is 2n = 46.
distribution
The species are common in desert areas in northern Mexico and the southwestern United States.
Systematics
The genus is clearly differentiated from other genera of the family due to the morphology of the inflorescences, flowers and fruits and is therefore classified in its own subfamily Petalonychoidae. The genus includes five species:
- Petalonyx crenatus A.Gray ex S.Watson : It was first described from Mexico.
- Petalonyx linearis Greene : It occurs in southern California, southwestern Arizona and Mexico.
- Petalonyx nitidus S. Watson : It is found in California, Nevada, northwestern Arizona and southwestern Utah.
- Petalonyx parryi A. Gray : It occurs in Arizona, Nevada and Utah.
-
Petalonyx thurberi A. Gray : There are two subspecies:
- Petalonyx thurberi subsp. gilmanii (Munz) WS Davis & HJ Thomps. : It occurs in southeastern California.
- Petalonyx thurberi subsp. thurberi : It occurs in Arizona, southern California, southern Nevada and Mexico.
The genus was first described by Asa Gray , the description of the subfamily was done in the context of extensive systematic work on the family by Maximilian Weigend in 1997 and 2006.
proof
- Maximilian Weigend: Loasaceae. In: Klaus Kubitzki (Ed.): The Families and Genera of Vascular Plants . Volume 6: Flowering Plants, Dicotyledons: Celastrales, Oxalidales, Rosales, Cornales, Ericales . Springer, Berlin / Heidelberg / New York 2004, ISBN 3-540-06512-1 , pp. 248 (English, limited preview in Google Book search).
- Maximilian Weigend: Familial and generic classification , online , accessed on July 19, 2008
Individual evidence
Most of the information in this article has been taken from the sources given under references; the following sources are also cited:
- ↑ a b c d e Petalonyx in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved October 25, 2018.
- ↑ See: International Code of Botanical Nomenclature (Vienna Code), Art. 30.5, Ex. 10, Online
