Flora of North America species comparison

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Ceanothus lemmonii

Ceanothus prostratus

Lemmon's ceanothus

mahala mat, prostrate ceanothus, squawcarpet
Habit Shrubs, evergreen, 0.5–1 m. Stems ascending to spreading, not rooting at nodes; branchlets pale green to grayish green and glaucous, not thorn-tipped, round in cross section, flexible to ± rigid, sparsely villosulous. 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

petiole 2–6 mm;

blade flat, narrowly elliptic to oblong-elliptic, 13–35 × 6–15 mm, base cuneate to rounded, margins serrulate to denticulate most of length, not revolute, not wavy, teeth 34–45, apex acute to obtuse, abaxial surface pale green to grayish green and glaucous, villosulous, especially on veins, adaxial surface green, strigillose; pinnately veined or weakly 3-veined from base.

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, umbel-like to racemelike, 2–6.5 cm.

axillary, 0.9–2 cm.
Flowers

sepals, petals, and nectary pale to deep blue.

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

3–4 mm wide, lobed near apex;

valves smooth, crested.

6–9 mm wide, lobed;

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

= 24.

= 24.

Ceanothus lemmonii

Ceanothus prostratus
Phenology Flowering Apr–May.
Habitat Rocky slopes and flats, open sites, conifer forests, oak and pine woodlands.
Elevation 200–1300 m. (700–4300 ft.)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; ID; NV; OR; WA
[WildflowerSearch map]
[BONAP county map]
Discussion

Ceanothus lemmonii occurs in the inner North Coast Ranges, Klamath Mountains, and the western slope of the Cascade Range and northern Sierra Nevada. H. McMinn (1944) reported putative hybrids with C. foliosus, C. integerrimus, and C. oliganthus var. sorediatus.

(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 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. 94. FNA vol. 12, p. 104.
Parent taxa Rhamnaceae > Ceanothus > subg. Ceanothus Rhamnaceae > Ceanothus > subg. Cerastes
Sibling taxa
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. 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. prostratus var. occidentalis, C. prostratus var. prostratus
Name authority Parry: Proc. Davenport Acad. Nat. Sci. 5: 192. (1889) — (as lemmoni) 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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