Eriastrum

Eriastrum eremicum ssp. yageri

Eriastrum eremicum subsp. yageri

Erisastrum is a genus of at least 16 species of mostly annuals (one perennial) native to arid regions of southwestern North America.  It is currently the subject of much revisionary study and several species have been described in recent years.  Active research on this interesting genus in ongoing.

The genus is easily recognized by its caulescent habit with dense, arachnose- wooly pubescence of the herbage, leaves generally pinnately lobed, calyx with unequal lobes, and blue to lavender corollas with a yellow throat.

Biogeography

Eriastrum is most diverse in California.

worldwide distribution of Eriastrum

worldwide distribution of Eriastrum

Phylogeny

Molecular evidence places Eriastrum as sister to a clade comprised of Langloisia and Loeseliastrum. 

Taxonomy

  1. Eriastrum abramsii (Elmer) H. Mason
  2. Eriastrum brandegeeae H. Mason
  3. Eriastrum densifolium (Benth.) H. Mason
    • E. densifolium (Benth.) H. Mason subsp. austromontanum (T. T. Craig) H. Mason
    • E. densifolium (Benth.) H. Mason subsp. densifolium
    • E. densifolium (Benth.) H. Mason subsp. elongatum (Benth.) H. Mason
    • E. densifolium (Benth.) H. Mason subsp. mohaviensis (T.T. Craig) H. Mason
    • E. densifolium (Benth.) H. Mason subsp. sanctorum (Milliken) H. Mason
  4. Eriastrum diffusum (A. Gray) H. Mason
  5. Eriastrum eremicum (Jeps.) H. Mason
    • E. eremicum (Jeps.) H. Mason subsp. eremicum
    • E. eremicum (Jeps.) H. Mason subsp. yageri (M.E. Jones) H. Mason
    • E. eremicum (Jeps.) H. Mason subsp. zionis (T.T. Craig) De Groot
  6. Eriastrum ertterae D. Gowen
  7. Eriastrum filifolium (Nutt.) Wooton & Standley
  8. Eriastrum harwoodii (T.T. Craig) D. Gowen
  9. Eriastrum hooveri (Jeps.) H. Mason
  10. Eriastrum luteum (Benth.) H. Mason
  11. Eriastrum pluriflorum (A. Heller) H. Mason
    • E. pluriflorum (A. Heller) H. Mason subsp. pluriflorum
    • E. pluriflorum (A. Heller) H. Mason subsp. sherman-hoytae (T.T. Craig) H. Mason
  12. Eriastrum rosamondense D. Gowen
  13. Eriastrum sapphirinum (Eastw.) H. Mason
    • E. sapphirinum (Eastw.) H. Mason subsp. sapphirinum
    • E. sapphirinum (Eastw.) H. Mason subsp. dasyanthum (Brand) H. Mason
  14. Eriastrum signatum D. Gowen
  15. Eriastrum sparsiflorum (Eastw.) H. Mason
  16. Eriastrum tracyi H. Mason
  17. Eriastrum virgatum (Benth.) H. Mason
  18. Eriastrum wilcoxii (A. Nels.) H. Mason

KEY TO ERIASTRUM (modified from Craig 1934a, 1934b, Gowen 2008, De Groot 2011, De Groot et al. 2013)

1. Woody-based perennial; corolla 15-30 mm long; the tube 2-3 X longer than calyx (E. densifolium)
23. Corolla 22-32 mm long
24. Corolla 25-32 mm long, lobes 1/3 X tube, plants lanate…E. d. sanctorum
24′. Corolla 22-25 mm. long, lobes almost as long as tube; plants glabrous or nearly so…E. d. densifolium
23′. Corolla 14-19 mm long
25. Leaves commonly recurved, pinnatifid; the lobes about as long as width of rachis; flowers pale blue or lavender; plant canescent-lanate…E. d. mohaviensis
25′. Leaves usually ascending, lobed or entire; the lobes 2-10 X as long as width of rachis; flowers deep blue; plant lanate to sub-glabrous
26. Bracts of inflorescence (0)-3-5-(7) lobed; plants 20-90 cm high with many axillary inflorescences which are rarely more than 10 (-15) flowered; leaves lobed or entire; plant thinly canescent-lanate…E. d. elongatum
26′. Bracts of flower clusters commonly 5-9-lobed; plants 15-45 cm. high; inflorescences terminal, commonly 15 (-20) flowered; leaves 2-15-lobed, never entire; plant sub-glabrous…E. d. austromontanum
1′. Annual; corolla 7-18 mm long; the tube usually > calyx or up to 2 X
3. Corolla >10 mm long, rarely to 11 mm
4. Anthers exserted beyond sinus of corolla
5.Corolla lobes bright yellow…E. luteum
5.’ Corolla lobes white or blue, rarely light yellow
6. Stamens unequal in length
7. Corolla white to lavender
8. Leaves entire; Los Angeles Co. CA…E. rosamondense
8.’ Leaves usually with a pair of lateral lobes; San Bernardino Co. CA and eastward…E. diffusum
7’. Corolla blue…E. filifolium
6’. Stamens equal in length
9. Plant glandular pubescent…E.sparsiflorum
9′. Plant not glandular-pubescent
10. Corolla lobes bluish, with dark colored spot at base; rounded…E.signatum
10′. Corolla lobes yellowish or whitish, without dark colored spot at base,; apiculate…E. harwoodii
4′ Anthers included or at the sinus of the corolla.
11. Upper leaves/bracts 3–7 lobed; inflorescences many flowered, densely bracteate…E. abramsii
11′. Upper leaves/bracts 1–3 (-5) lobed; inflorescences few flowered, bracts few
12. Corolla 7–10 mm long; seeds 3(–6) per capsule
13. Corolla lobes 1.2–1.5 mm wide; stamens 0.75–1.5 mm long, filaments = anther length…E. tracyi
13′. Corolla lobes 0.9–1.1 mm wide; stamens 1.5–2 mm long, filaments 2 X anther length…E. brandegeeae
12′. Corolla 5–7 mm long; seeds 6–12 per capsule
14. Stamens 1-1.25 mm long…E. hooveri
14’. Stamens 1.5-2.5 mm long…E. ertterae
3’. Corolla 10 mm long or longer, commonly > 12 mm
15. Flowers zygomorphic (markedly to slightly so), stamens markedly unequal in length…(E. eremicum)
16. Leaves with 5-9 lobes…E. e. eremicum
16′. Leaves commonly linear or 3 (-5) lobed
17. Corolla markedly zygomorphic; the lobes 2/3 X tube, more than 2 X as long as broad; lobes acute…E. e. zionis
17′. Corolla slightly zygomorphic; the lobes + tube, the lobes less than 2 X as long as broad; lobes rounded…E. e. yageri
7′. Flowers actinomorphic or nearly so, stamens of almost equal length
18. Stamens adnate well below corolla sinuses (E. pluriflorum)
19. Flowers deep blue; lobes rarely less than 2/3 X as long as tube…E. p. pluriflorum
19′. Flowers pale blue; lobes not more than 1/2 X length of tube…E. p. sherman-hoytae
18’. Stamens adnate at or just below corolla sinuses
20. Flowers large; 15-22 mm long…E. virgatum
20′. Flowers smaller 10-15 (-17.5 mm long
21. Anthers short < 1 mm long and corolla lobes < 5 mm long…E. wilcoxii
21’. Anthers elongate > 1 mm long and corolla lobes > 5 mm long (E. sapphirinum)
22. Flowers 1-3 per inflorescence…E. s. sapphirinum
22′. Flowers 3 or more per inflorescence…E. s. dasyanthum

References

Craig, T. 1934a. A revision of the subgenus Hugelia of the genus Gilia (Polemoniaceae). Bulletin of the Torrey Botanical Club 61: 385–397.

Craig, T. 1934b. A revision of the subgenus Hugelia of the genus Gilia (Polemoniaceae). Bulletin of the Torrey Botanical Club 61: 411–428.

Gowen, D. 2013.  Two New Species of Eriastrum (Polemoniaceae) From California. Journal of the Botanical Research Institute of Texas.  7: 21-24.

Gowen, D. 2008.  New Taxa Following a Reassessment of Eriastrum sparsiflorum (Polemoniaceae).  Madroño 55:82-87.

De Groot, S. J. 2011. Spatial analysis of morphology in Eriastrum eremicum (Polemoniaceae). Systematic Botany 36: 449–464.

De Groot, S., D. Gowen, and R. Patterson. 2013. Eriastrum, in Jepson Flora Project (eds.)  Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=86188, accessed on Dec 20 2014.

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