Dwarf sunflowers
| Dwarf sunflowers | ||||||||||||
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Five-nerved dwarf sunflower ( Helianthella quinquenervis ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Helianthella | ||||||||||||
| Torr. & Gray |
The helianthella ( Helianthella ) are a genus in the subfamily of Asteroideae within the family of the daisy family (Asteraceae). The nine to ten species are distributed from Canada to Mexico.
description
Vegetative characteristics
Helianthella species grow as perennial herbaceous plants which, depending on the species, usually reach heights of 20 to 150 centimeters. The upright stems are mostly branched.
The opposite and alternate , basal and distributed on the stems arranged leaves are mostly petiolate. The leaf blade is simple with three or five leaf veins already at or near the blade base. The leaf margin is smooth. The leaf surfaces are smooth or hairy.
Generative characteristics
The head-shaped inflorescences are individually terminal or in pairs up to 15 together in branched, umbrella -clustered inflorescences . The circular flower heads are 1 to 5 centimeters in diameter. In more or less three rows there are 22 to 32 bracts ; they are almost the same to very different in shape and size. The bottoms of the flower head are more or less convex. There are chaff leaves.
The flower heads contain eight to 21 ray-flowers and 30 to over 200 tubular flowers. The ungeschlechtigen ray florets (= ray flowers) are yellow and the tongue ends tridentate. The hermaphroditic, fertile tubular flowers (= disc flowers) are usually yellow or brown to purple in color with five corolla lobes.
The angular achenes are brownish. The pappus consists of two awl-shaped scales and sometimes in addition to more than four smaller, slit scales, which sometimes can all be more or less fused; the pappus can also be absent.
Systematics and distribution
The genus Helianthella was established in 1842 by John Torrey and Asa Gray in Synoptical Flora of North America , 2, page 333. The botanical genus name Helianthella is derived from the sunflower genus name Helianthus and the Latin - ella as a diminutive ( diminutive ). Type species is Helianthella uniflora (Nuttall) Torrey & A.Gray
The genus Helianthella belongs to the subtribe Enceliinae from the tribe Heliantheae in the subfamily of the Asteroideae within the sunflower family (Asteraceae).
The distribution area of the genus Helianthella extends from northern Mexico with four species to western North America with six species.
There are nine to ten species in the genus Helianthella :
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Helianthella californica A.Gray : The three subspecies occur in the western United States :
- Helianthella californica A. Gray subsp. californica : It occurs in California.
- Helianthella californica subsp. nevadensis (Greene) WAWeber : It occurs in California, Oregon and northwestern Nevada.
- Helianthella californica subsp. shastensis (WAWeber) WAWeber : It occurs in California.
- Helianthella castanea Greene : This endemic is only known from the San Francisco Bay area in California and thrives at altitudes from 0 to 1200 meters.
- Helianthella ciliata S.F.Blake : The home is Mexico.
- Helianthella durangensis B.L. Turner : It only occurs in the northern Mexican state of Durango .
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Helianthella gypsophila B.L. Turner : The two varieties occur in Mexico:
- Helianthella gypsophila var. Calcarea B.L. Turner
- Helianthella gypsophila B.L. Turner var. Gypsophila
- Helianthella mexicana A.Gray : It occurs in the northern Mexican states of San Luis Potosi and Zacatecas .
- Helianthella microcephala (A. Gray) A. Gray : It thrives in altitudes from 1700 to 2800 meters comes in the Colorado Plateau province in Arizona , Colorado , New Mexico and Utah before
- Helianthella parryi A.Gray : It thrives in mountain forests at altitudes of 2400 to 3600 meters in Arizona, Colorado and New Mexico.
- Five-nerved dwarf sunflower ( Helianthella quinquenervis (Hook.) A.Gray ): It thrives mainly in the Rocky Mountains , Great Basin Ranges and Black Hills at altitudes of 1400 to 3600 meters in the US states: Arizona, Colorado, Idaho , Montana , Nevada , Oregon , South Dakota , Wyoming and New Mexico and in the northern Mexican states of Chihuahua and Nuevo León .
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Helianthella uniflora (Nuttall) Torrey & A.Gray : The two varieties thrive at altitudes of 300 to 3400 meters:
- Helianthella uniflora var. Douglasii (Torr. & A.Gray) WAWeber : It is found in southern British Columbia , Washington, Oregon and northern Idaho.
- Helianthella uniflora (Nuttall) Torrey & A.Gray var. Uniflora : It is found in Colorado, Idaho, Utah, Wyoming, Montana, Arizona and Nevada.
No longer belong to the genus:
- Helianthella argophylla (DCEaton) A.Gray ⇒ Tithonia argophylla D.C.Eaton
- Helianthella covillei A.Nelson ⇒ Enceliopsis covillei (A.Nelson) SFBlake
- Helianthella grandiflora Torr. & A.Gray ⇒ Phoebanthus grandiflora (Torr. & A.Gray) SFBlake
- Helianthella tenuifolius Torr. & A.Gray ⇒ Phoebanthus tenuifolius (Torr. & A.Gray) SFBlake
swell
literature
- William A. Weber: Helianthella , pp. 114-116 - same text online as printed work , In: Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico , Volume 21 - Magnoliophyta: Asteridae (in part) : Asteraceae, part 3 , Oxford University Press, New York and Oxford, June 30, 2006, ISBN 0-19-530565-5 .
- William A. Weber: New names and combinations in Asteraceae: Heliantheae-Ecliptinae. , in Phytologia , Volume 85, Issue 1, 1998, pp. 19-21.
Individual evidence
- ↑ a b c d e f g Helianthella in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved January 20, 2019.
- ↑ a b c d e William A. Weber: Helianthella , pp. 114-116 - text online with the same text as the printed work , In: Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico , Volume 21 - Magnoliophyta : Asteridae (in part): Asteraceae, part 3 , Oxford University Press, New York and Oxford, June 30, 2006, ISBN 0-19-530565-5 .
