Flora of North America species comparison

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Ceanothus cuneatus

Ceanothus prostratus

buck brush, common buckbrush, narrow-leaf buckthorn, sedge-leaf buckthorn, wedgeleaf cuneatus

mahala mat, prostrate ceanothus, squawcarpet
Habit Shrubs, 0.5–3.5 m. Stems erect, ascending, or spreading, not rooting at nodes; branchlets grayish brown to brown, rigid or flexible, glabrate, puberulent, or tomentulose, hairs straight. Shrubs, 0.1–0.3 m, matlike to moundlike.
Stems

prostrate, spreading, or ascending, rooting at distal nodes;

branchlets reddish brown, ± flexible, puberulent, glabrescent.
Leaves

usually both fascicled and not fascicled on same plant, rarely none fascicled;

petiole 1–3 mm;

blade flat to cupped, elliptic, oblanceolate, obovate, or orbiculate, 4–22(–30) × 3–12(–22) mm, base rounded, margins thick, not revolute, entire or denticulate distal to middle, teeth 0–9, apex obtuse, rounded, truncate, or retuse, abaxial surface pale green, glabrate or glabrous, adaxial surface green, glabrous.

not fascicled, crowded, usually longer than internodes and obscuring them;

petiole 1–3 mm;

blade flat to ± cupped, elliptic to obovate, 6–30 × 4–16 mm, base cuneate, margins sometimes thick, not revolute, sometimes wavy, sharply dentate to spinose-dentate, teeth 3–9, apex rounded, abaxial surface pale green, glabrous except sparsely strigillose on veins, adaxial surface dark green, shiny, glabrate.
Inflorescences

axillary or terminal, 0.8–2.5 cm.

axillary, 0.9–2 cm.
Flowers

sepals, petals, and nectary white to lavender or blue.

sepals, petals, and nectary pale to deep blue or purplish blue.
Capsules

4–6 mm wide, weakly lobed;

valves smooth, horns subapical, prominent, erect, intermediate ridges absent.

6–9 mm wide, lobed;

valves smooth to rugulose, horns subapical, prominent, erect or spreading, rugose or not, intermediate ridges present.
2n

= 24.

Ceanothus cuneatus

Ceanothus prostratus
Distribution
from FNA
CA; OR; nw Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; ID; NV; OR; WA
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[BONAP county map]
Discussion

Varieties 4 (4 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Varieties 2 (2 in the flora).

Putative hybrids between Ceanothus prostratus and C. velutinus var. velutinus, named C. ×rugosus, have been reported from northeastern California (H. McMinn 1944). A rare putative hybrid between C. prostratus and C. cordulatus in the Lake Tahoe basin has been named C. ×serrulatus. Both C. ×rugosus and C. ×serrulatus are intersubgeneric hybrids. Formally named hybrids between C. prostratus and C. cuneatus var. cuneatus include C. ×flexilis and possibly C. ×connivens, but the latter could have C. fresnensis as one of the parents rather than C. prostratus.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Leaf blades of fascicled and non-fascicled leaves elliptic to widely oblanceolate, length usually 2+ times width; sepals, petals, and nectaries usually white, sometimes pale blue or pale lavender.
var. cuneatus
1. Leaf blades of fascicled and non-fascicled leaves widely oblanceolate, widely obovate, or orbiculate, length usually less than 2 times width, or of fascicled leaves elliptic to narrowly oblanceolate (in var. fascicularis); sepals, petals, and nectaries usually lavender to blue, sometimes pale blue, rarely white.
→ 2
2. Leaf blades of fascicled leaves elliptic to narrowly oblanceolate, 9–15 × 3–6 mm, length usually 2+ times width.
var. fascicularis
2. Leaf blades of fascicled leaves widely oblanceolate, widely obovate, or orbiculate, 4–15 × 3–12 mm, length less than 2 times width.
→ 3
3. Leaf blade margins usually entire, rarely 1–4-toothed, apices rounded, truncate, or retuse.
var. ramulosus
3. Leaf blade margins 5–9-toothed, apices rounded to truncate.
var. rigidus
1. Leaf blades flat, margins not wavy, teeth usually 3–5(–7); capsule horns erect.
var. prostratus
1. Leaf blades slightly folded lengthwise adaxially, margins ± wavy, teeth 5–9; capsule horns spreading.
var. occidentalis
Source FNA vol. 12, p. 99. FNA vol. 12, p. 104.
Parent taxa Rhamnaceae > Ceanothus > subg. Cerastes Rhamnaceae > Ceanothus > subg. Cerastes
Sibling taxa
C. americanus, C. arboreus, C. arcuatus, C. confusus, C. cordulatus, C. crassifolius, C. cyaneus, C. dentatus, C. divergens, C. diversifolius, C. fendleri, C. ferrisiae, C. foliosus, C. fresnensis, C. gloriosus, C. griseus, C. hearstiorum, C. herbaceus, C. impressus, C. incanus, C. integerrimus, C. jepsonii, C. lemmonii, C. leucodermis, C. maritimus, C. martini, C. masonii, C. megacarpus, C. microphyllus, C. oliganthus, C. ophiochilus, C. otayensis, C. palmeri, C. papillosus, C. parryi, C. parvifolius, C. pauciflorus, C. perplexans, C. pinetorum, C. prostratus, C. pumilus, C. purpureus, C. roderickii, C. sanguineus, C. sonomensis, C. spinosus, C. thyrsiflorus, C. tomentosus, C. velutinus, C. verrucosus
C. americanus, C. arboreus, C. arcuatus, C. confusus, C. cordulatus, C. crassifolius, C. cuneatus, C. cyaneus, C. dentatus, C. divergens, C. diversifolius, C. fendleri, C. ferrisiae, C. foliosus, C. fresnensis, C. gloriosus, C. griseus, C. hearstiorum, C. herbaceus, C. impressus, C. incanus, C. integerrimus, C. jepsonii, C. lemmonii, C. leucodermis, C. maritimus, C. martini, C. masonii, C. megacarpus, C. microphyllus, C. oliganthus, C. ophiochilus, C. otayensis, C. palmeri, C. papillosus, C. parryi, C. parvifolius, C. pauciflorus, C. perplexans, C. pinetorum, C. pumilus, C. purpureus, C. roderickii, C. sanguineus, C. sonomensis, C. spinosus, C. thyrsiflorus, C. tomentosus, C. velutinus, C. verrucosus
Subordinate taxa
C. cuneatus var. cuneatus, C. cuneatus var. fascicularis, C. cuneatus var. ramulosus, C. cuneatus var. rigidus
C. prostratus var. occidentalis, C. prostratus var. prostratus
Synonyms Rhamnus cuneata
Name authority (Hooker) Nuttall: in J. Torrey and A. Gray, Fl. N. Amer. 1: 267. (1838) Bentham: Pl. Hartw., 302. (1849)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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