Jamesia
| Jamesia | ||||||||||||
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Jamesia americana |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Jamesia | ||||||||||||
| Torr. & Gray |
Jamesia is a genus of plants fromthe hydrangea family (Hydrangeaceae). It includes two species native to southern North America.
description
Jamesia are deciduous shrubs . The leaves are stalked and serrated on the edge.
The inflorescences are zymous panicles , the cymes are dichasias , sterile flowers are absent.
The four to five sepals are hinged on top of each other. The four to five petals, which are arranged like tiles or flaps, are spatulate and white to pink.
The stamens of the 8 to 10 stamens are awl-shaped, the connective of the anthers protrudes at their ends. The stylus are short with long stylus branches or the stylus branches are not overgrown. The medium-sized ovary is three to five-fold. The fruit is a capsule that, when ripe, opens with a crevice in the septum to release the approximately twenty (but less than six per compartment), 0.5 to 1 millimeter long, winged seeds.
The number of chromosomes is n = 16.
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distribution
The distribution area of the genus extends from the Great American Basin to the north and southwest of Mexico, they are particularly common in the southern Rocky Mountains . Jamesia are found exclusively in mountain ranges.
Systematics
The genus was first described by John Torrey and Samuel Frederick Gray in 1840 , the type species is Jamesia americana . Within the family it is placed in the subfamily Jamesioideae , of which it is a type genus. It includes two types:
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Jamesia americana
Torr. & A. Gray . With the varieties:
- Jamesia americana var. Americana : It occurs in Arizona, Wyoming, Colorado, New Mexico and Mexico at altitudes between 1500 and 3800 meters above sea level.
- Jamesia americana var. Macrocalyx (Small) Engler : It occurs only in Utah at altitudes between 1700 and 3700 meters above sea level.
- Jamesia americana var. Rosea Purpus ex CK Schneider : It occurs in California and Nevada at altitudes between 2000 and 3700 meters above sea level.
- Jamesia americana var. Zionis N. H. Holmgren & PK Holmgren : It occurs only in Utah at altitudes between 1200 and 2500 meters above sea level.
- Jamesia tetrapetala N.H. Holmgren & PKHolmgren : It occurs only in Nevada and Utah at altitudes between 2000 and 3000 meters above sea level.
literature
- L. Hufford: Hydrangeaceae. In: Klaus Kubitzki (Ed.): The Families and Genera of Vascular Plants - Volume VI - Flowering Plants - Dicotyledons - Celastrales, Oxalidales, Rosales, Cornales, Ericales , 2004, pp. 209-210, ISBN 978-3-540- 06512-8
