Flora of North America species comparison

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Ceanothus lemmonii

Ceanothus arcuatus

Lemmon's ceanothus

arching ceanothus
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, 0.3–0.8 m, moundlike.
Stems

ascending or spreading, not rooting at nodes;

branchlets brown to grayish brown, ± rigid, tomentulose, 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.

sometimes fascicled, axillary short shoots ascending to spreading;

petiole 1–2 mm;

blade flat, elliptic to oblanceolate, 4–10 × 2–5 mm, base rounded, margins thick, not revolute, usually entire, rarely denticulate near apex, teeth 1–3, apex rounded to obtuse, abaxial surface green to pale green, glabrate, adaxial surface pale green, glabrous.
Inflorescences

axillary or terminal, umbel-like to racemelike, 2–6.5 cm.

axillary or terminal, 0.8–2.5 cm.
Flowers

sepals, petals, and nectary pale to deep blue.

sepals and petals white to pale blue;

nectary pale blue or yellow tinged.
Capsules

3–4 mm wide, lobed near apex;

valves smooth, crested.

4–6 mm wide, not to weakly lobed;

valves smooth to rugulose, horns subapical, prominent, erect, intermediate ridges absent.
2n

= 24.

Ceanothus lemmonii

Ceanothus arcuatus
Phenology Flowering Apr–May. Flowering May–Jun.
Habitat Rocky slopes and flats, open sites, conifer forests, oak and pine woodlands. Granitic or serpentine soils, conifer forests.
Elevation 200–1300 m. (700–4300 ft.) 900–2300 m. (3000–7500 ft.)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; OR
[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.)

Ceanothus arcuatus was explicitly described as a species by McMinn but inexplicably treated as a hybrid between C. fresnensis and C. cuneatus by P. A. Munz (1959). Munz may have been influenced by McMinn’s hypothesis that C. arcuatus was derived through hybridization between the two species. Some specimens from the Klamath Mountains have been either interpreted as C. cuneatus or misidentified as hybrids between C. pumilus and C. cuneatus. Populations of C. arcuatus are relatively uniform throughout their geographic distribution and often represent the dominant understory shrub in conifer forests of the Klamath Mountains and Sierra Nevada. Ceanothus arcuatus occurs primarily on metamorphic substrates in the Klamath Mountains and the northern Sierra Nevada, but in the central Sierra Nevada (Nevada County south to Madera County), the most common substrate is granitic.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 12, p. 94. FNA vol. 12, p. 101.
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. 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. prostratus, C. pumilus, C. purpureus, C. roderickii, C. sanguineus, C. sonomensis, C. spinosus, C. thyrsiflorus, C. tomentosus, C. velutinus, C. verrucosus
Name authority Parry: Proc. Davenport Acad. Nat. Sci. 5: 192. (1889) — (as lemmoni) McMinn: in M. van Rensselaer and H. McMinn, Ceanothus, 247, fig. 82. (1942)
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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