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Helianthella castanea

(Diablo Rock-Rose)

Overview

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Vulnerable

Threat status

Interesting Facts

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Common Names

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Common Names in English:

Diablo Rock-Rose, Mt. Diablo Helianthella

Description

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Family Compositae

The largest family of flowering plants , the Compositae (Asteraceae), comprising about 1,100 genera and more than 20,000 species and characterized by many small flowers arranged in a head looking like a single flower and subtended by an involucre of bracts. A head may consist of both ray flowers and disk flowers, as in the sunflower, of disk flowers only, as in the burdock, or of ray flowers only, as in the dandelion.

Genus Helianthella

Perennials , 20-150 cm. Stems erect , usually branched. Leaves basal and cauline; opposite (proximal ) and alternate; usually petiolate (at least proximal) ; blades (usually 3- or 5-nerved from at or near bases ) elliptic , lanceolate, lance-linear , linear , oblanceolate , ovate , ovate-lanceolate, or spatulate , bases mostly cuneate, margins entire, faces glabrous or hairy . Heads radiate , borne singly or (2-15+) in corymbiform arrays. Involucres campanulate to hemispheric or broader, 10-50 mm diam. Phyllaries persistent , 22-32+ in ± 3 series (mostly deltate-ovate or ovate to lanceolate, linear, or oblong , subequal or unequal, outer sometimes foliaceous ). Receptacles ± convex , paleate (paleae falling with cypselae, conduplicate , scarious or chartaceous ). Ray florets 8-21, neuter ; corollas ± yellow. Disc florets 30-200+, bisexual , fertile ; corollas yellow or purple to brown, tubes shorter than or equaling throats , lobes 5, deltate (abaxially hairy). Cypselae (brownish) ± compressed , obovate to obcordate (margins usually ± winged , usually ± ciliate , faces glabrous or strigose ) ; pappi 0, or persistent, of 2 ± subulate scales plus 0-4+ shorter, lacerate scales (sometimes all ± connate ). x = 15.

Species 9: w North America, n Mexico.[1]

Physical Description

Species Helianthella castanea

Plants 15-45 cm. Cauline leaves: largest proximal to mid stems; blades sometimes ± 3-nerved, oblong or elliptic to broadly-oblanceolate, 10-15 cm, faces sparsely hirsute (mostly abaxially and near margins ). Heads borne singly, erect . Involucres hemispheric , 25-40 mm diam. Phyllaries (usually outer 3-4+ foliaceous , 3-10 cm, curling over heads ) lanceolate to lance-oblong (margins usually ciliate , abaxial faces densely pubescent or glabrate ). Paleae chartaceous , relatively firm. Ray florets 12-21; laminae (10-) 20-30 mm. Disc corollas yellow. Cypselae weakly compressed (plump in middles , edges thin, faces, glabrous ) ; pappi 0 or of 2 ± subulate scales . 2n = 30. [source]

Habit: Forb/herb

Flowers: Bloom Period: April, May.

Habitat

Grassy hillsides; 0-1200 m [2].

Typically found at an altitude of 0 to 862 meters (0 to 2,828 feet).[3]

Biology

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Reproduction

Duration: Perennial

Taxonomy

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Notes

Name Status: Accepted Name . Latest taxonomic scrutiny: 15-Mar-2000

Similar Species

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Members of the genus Helianthella

ZipcodeZoo has pages for 12 species, subspecies, varieties, forms, and cultivars in this genus:

H. californica (California Helianthella) · H. californica Gray var. shastensis W.A.Weber (Shasta Helianthella) · H. californica var. californica (California Helianthella) · H. californica var. nevadensis (Nevada Helianthella) · H. californica var. shastensis (Shasta Helianthella) · H. castanea (Diablo Rock-Rose) · H. microcephala (Purpledisk Helianthella) · H. parryi (Dwarf Rockrose) · H. quinquenervis (Fivenerve Helianthella) · H. uniflora (Oneflower Helianthella) · H. uniflora var. douglasii (Douglas' Helianthella) · H. uniflora var. uniflora (Oneflower Helianthella)

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal February 01, 2008:

Identifiers

Footnotes

  1. William A. Weber "Helianthella". in Flora of North America Vol. 21 Page 65, 66, 67, 114. Oxford University Press. Online at EFloras.org. [back]
  2. "Helianthella castanea". in Flora of North America Vol. 21 Page 115, 117. Oxford University Press. Online at EFloras.org. [back]
  3. Mean = 365.000 meters (1,197.507 feet), Standard Deviation = 317.220 based on 22 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 7/15/2012