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Ceanothus rigidus

Higher Taxonomy
Family: RhamnaceaeView DescriptionDichotomous Key

Common Name: BUCKTHORN FAMILY
Habit: [Perennial herb] shrub, tree, generally erect, often thorny. Leaf: simple, generally alternate, often clustered on short-shoots; stipules generally present, occasionally modified into spines; generally petioled; blade pinnate-veined or 1--5-ribbed from base. Inflorescence: cyme, panicle, umbel, or flowers 1 or clustered in axils or on short-shoots. Flower: generally bisexual, radial; hypanthium subtending, surrounding, or partly fused to ovary; sepals 4--5; petals 0, 4--5, generally clawed; stamens 0, 4--5, alternate sepals, attached to hypanthium top, each generally fitting into a petal concavity; disk (0 or) between stamens, ovary, thin to fleshy, entire or lobed, free from ovary, adherent or fused to hypanthium; ovary superior or +- inferior, chambers [1]2--4, 1--2-ovuled, style 1, stigma entire or 2--3-lobed. Fruit: capsule, drupe.
Genera In Family: 50--52 genera, 950 species: especially tropics, subtropics some cultivated (Ceanothus; Frangula; Rhamnus; Ziziphus).
eFlora Treatment Author: John O. Sawyer, Jr., except as noted
Scientific Editor: Steve Boyd, Thomas J. Rosatti.
Genus: CeanothusView DescriptionDichotomous Key

Common Name: CALIFORNIA-LILAC
Habit: Shrub, tree-like or not, generally erect or mat- to mound-like. Stem: branches generally arranged like leaves; twigs thorn-like or not, generally not angled. Leaf: alternate or opposite, some clustered on short-shoots or not, deciduous or evergreen; stipules scale-like, thin, deciduous, or knob-like, corky, thick, base persistent; blade flat or wavy, tip generally acute to obtuse, margin thick (i.e., thicker than adjacent blade) or not, rolled under or not, wavy or not, entire or gland- or sharp-toothed, glands generally dark, teeth pale, alternate blade 1--3-ribbed from base, generally thin, opposite blade 1-ribbed from base, thick, firm. Inflorescence: umbel-, raceme-, or panicle-like aggregations of few-flowered clusters, axillary or terminal; pedicels white to deep blue or pink. Flower: conspicuous, generally < 5 mm; hypanthium surrounding fleshy disk below ovary base, in fruit thick, not splitting; sepals generally 5, lance-deltate, incurved, colored like petals, persistent; petals generally 5, blade hood-like, white to deep blue or pink; stamens generally 5, opposite petals; ovary 1/2-inferior, 3-lobed, chambers 3, each 1-ovuled, styles 3. Fruit: capsule, +- spheric, generally +- 3-lobed, generally smooth, 3-ridged or not, horned or not. Seed: 3, 2--5 mm.
Species In Genus: +- 55 species: North America. Etymology: (Greek: thorny pl) Note: Hybrids common (named hybrids not recognized here), discussed in Fross & Wilken; hybrid forms do not key easily. As recircumscribed here, Ceanothus greggii A. Gray restricted to Mexico.
eFlora Treatment Author: Dieter H. Wilken

Ceanothus rigidus Nutt.
NATIVE
Habit: Plant mound-like to +- erect, dense, < 1.5 m. Stem: erect to spreading, not rooting at nodes; twigs generally not angled, brown to gray-brown. Leaf: opposite, evergreen; stipules knob-like; petiole < 2 mm; blade 4--10 mm, 4--6 mm wide, length generally < 2 × width, widely obovate to round, adaxially generally shiny, dark green, glabrous, abaxially paler, short-strigose or puberulent, tip rounded to truncate, margin generally not thick, generally not rolled under, entire or teeth generally 5--9, sharp. Inflorescence: umbel-like, 0.5--2 cm. Flower: blue to lavender (white). Fruit: 4--6 mm wide, +- smooth; horns smooth, < 1 mm. Chromosomes: 2n=24.
Ecology: Sandy substrates, chaparral, closed-cone-pine forest; Elevation: < 400 m. Bioregional Distribution: CCo. Flowering Time: Mar--May Note: Were they to be recognized taxonomically, mound-like plants with white flowers would be assignable to Ceanothus rigidus var. albus Roof.
Synonyms: Ceanothus cuneatus (Hook.) Nutt. var. rigidus (Nutt.) Hoover
eFlora Treatment Author: Dieter H. Wilken
Jepson Online Interchange
Listed on CNPS Rare Plant Inventory

Previous taxon: Ceanothus purpureus
Next taxon: Ceanothus roderickii

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Citation for this treatment: Dieter H. Wilken 2016. Ceanothus rigidus, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=18436, accessed on December 05, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on December 05, 2016.


Ceanothus rigidus
click for enlargement
© 2012 Aaron E. Sims
Ceanothus rigidus
click for enlargement
© 2012 Aaron E. Sims
Ceanothus rigidus
click for enlargement
© 2012 Aaron E. Sims
Ceanothus rigidus
click for enlargement
© 2012 Aaron E. Sims
Ceanothus rigidus
click for enlargement
© 2012 Aaron E. Sims
Ceanothus rigidus
click for enlargement
© 2012 Aaron E. Sims

More photos of Ceanothus rigidus in CalPhotos


Geographic subdivisions for Ceanothus rigidus:
CCo.
Markers link to CCH specimen records. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues. Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
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map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.