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Ceanothus pauciflorus
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Rosales
Family:	Rhamnaceae
Genus:	Ceanothus
Species:	C. pauciflorus
Binomial name
Ceanothus pauciflorus Sessé and Moc. ex DC.
Synonyms
Species synonymy Ceanothus australis Rose Ceanothus cuneatus A.Gray Ceanothus franklinii (S.L.Welsh) S.L.Welsh Ceanothus greggii A.Gray Ceanothus greggii subsp. franklinii (S.L.Welsh) Kartesz & Gandhi Ceanothus greggii var. franklinii S.L.Welsh Ceanothus greggii var. lanuginosa M.E.Jones Ceanothus greggii var. orbicularis E.H.Kelso Ceanothus greggii var. vestitus (Greene) McMinn Ceanothus greggii subsp. vestitus (Greene) Thorne Ceanothus lanuginosus (M.E.Jones) Rose Ceanothus verrucosus var. greggii (A.Gray) K.Brandegee Ceanothus vestitus Greene Scutia pauciflora G.Don

Ceanothus pauciflorus, known by the common name Mojave ceanothus, is a species of flowering shrub in the buckthorn family, Rhamnaceae. It is native to the Southwestern United States (Arizona, California, New Mexico, Texas, and Utah) and Mexico, where it grows primarily in shrubland communities at moderate to high elevations. It is characterized by oppositely arranged leaves, corky stipules and white flowers. It was formerly known as Ceanothus greggii.

Description

Ceanothus pauciflorus is a many-branched shrub with woody parts that are gray in color and somewhat woolly. The flowers bloom in spring. Blooms are considered highly fragrant. C. pauciflorus is eagerly browsed by livestock and wild ungulates such as mule deer and desert bighorn sheep.

Morphology

This species is a shrub, around 0.2 to 4 m tall. The stem is ascending to erect, and generally branches from at or near the base. The twigs are colored a pale gray to more or less white, and are densely puberulent to short-tomentose. The evergreen leaves are arranged oppositely, on a petiole 1 to 3 mm long, and with a leaf blade 5 to 20 mm long by 3 to 19 mm wide. The adaxial surface of the leaf is concave, colored gray-green to yellow-green, and puberulent, becoming glabrous (smooth) in age. The abaxial surface of the leaf is convex, colored gray-green, and is glabrous or has short, curly hairs. The tip of the leaf is generally shaped acute to obtuse. The margins of the leaf may have teeth. The stipule is a knob-like structure.

The inflorescence is a small (less than 2 cm long) cluster of many white flowers on short lateral branches. The fruit is a horned capsule a few millimeters wide which bursts explosively to expel the three seeds inside, which require thermal scarification from wildfire before they can germinate.

Taxonomy

This species is a member of the Ceanothus subgenus Cerastes.

Classification

This species was originally discovered to science by Spanish botanists Martín Sessé y Lacasta and José Mariano Mociño on an expedition to western Mexico in 1790 to 1791. It was later described as Ceanothus pauciflorus by Augustin Pyramus de Candolle in 1825, based on the illustrations made by Sessé and Mociño expedition. Sessé and Mociño also collected a flowering specimen of Ceanothus, later determined to be Ceanothus pauciflorus.

Because Ceanothus pauciflorus was the first description of the plant, subsequent descriptions were reduced to synonyms. It was named by Asa Gray of Harvard University in 1853 as Ceanothus greggii in honor of its collector, Josiah Gregg, who found the plant in 1847 at the site of the Battle of Buena Vista in the Mexican state of Coahuila during the Mexican–American War. Edward Lee Greene named it as Ceanothus vestitus, but recent taxonomic analysis finds that C. vestitus does not have enough morphological evidence to warrant a separate taxon from C. pauciflorus.

Distribution and habitat

Ceanothus pauciflorus is widely distributed throughout the southwestern United States and northern Mexico. In the United States, it is found in the states of Arizona, California, Nevada, New Mexico, Texas, and Utah. It is widely distributed in Mexico, found from Baja California and Coahuila south to Oaxaca. In Baja California, it is found from the Sierra Juarez to the Sierra de la Asamblea. However, it is replaced in a portion of its range in California and Baja California with a close relative, Ceanothus perplexans. This species is found on a variety of habitats over its wide distribution, although it is almost always found in shrub-dominated communities like chaparral and matorral at moderate to high elevations (550 to 2600 m).

See also

• California chaparral and woodlands
• Mojave Desert
• Sky island

References

1. "Ceanothus pauciflorus". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 18 January 2022.
2. ^ Burge, Dylan O.; Zhukovsky, Katherine (2013). "Taxonomy of the Ceanothus vestitus Complex (Rhamnaceae)". Systematic Botany. 38 (2): 406–417. doi:10.1600/036364413X666750. ISSN 0363-6445. JSTOR 24546069. S2CID 85575909.
3. ^ Blakely, Larry, Desert Ceanothus, Ceanothus greggii A. Gray var. vestitus (E. Greene) McMinn (Rhamnaceae) Archived June 6, 2011, at the Wayback Machine, Who's in a Name? People Commemorated in Eastern Sierra Plant Names
4. John D. Stuart; John O. Sawyer; Andrea J. Pickart (2001). Trees and Shrubs of California. University of California Press. ISBN 978-0-520-22110-9.
5. "Ceanothus greggii – Desert Ceanothus – Southeastern Arizona Wildflowers and Plants". Fireflyforest.com. Retrieved 15 September 2018.
6. ^ "Species: Ceanothus greggii". Fs.fed.us. Retrieved 15 September 2018.
7. ^ Burge, Dylan O.; Wilken, Dieter H. (2020). "Ceanothus pauciflorus". Jepson eFlora (8 ed.). Jepson Flora Project. Archived from the original on 2017-08-29. Retrieved 18 January 2022.
8. Burge, Dylan O.; Zhukovsky, Katherine; Wilken, Dieter H. (2016-01-01). "A Taxonomic Conspectus of Ceanothus subgenus Cerastes (Rhamnaceae)". Systematic Botany. 40 (4): 950–961. doi:10.1600/036364415X689997. S2CID 85978200.
9. Rebman, J. P.; Gibson, J.; Rich, K. (2016). "Annotated checklist of the vascular plants of Baja California, Mexico" (PDF). San Diego Society of Natural History. 45: 242.

External links

Media related to Ceanothus pauciflorus at Wikimedia Commons

• Calflora Database: Ceanothus greggii (desert ceanothus)
• Jepson Manual treatment of Ceanothus greggii
• USDA Plants Profile for Ceanothus greggii (desert ceanothus)
• UC Photos gallery — Ceanothus greggii

• Ceanothus
• Flora of California
• Flora of Northeastern Mexico
• Flora of Northwestern Mexico
• Flora of the South-Central United States
• Flora of the Southwestern United States
• Flora of the California desert regions
• Flora of the Sierra Nevada (United States)
• North American desert flora
• Natural history of the California chaparral and woodlands
• Natural history of the Mojave Desert
• Natural history of the Peninsular Ranges
• Natural history of the Transverse Ranges
• Plants described in 1825
• Taxa named by Augustin Pyramus de Candolle