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tinted euphorbia, tinted woodland spurge

Marble Canyon spurge, Ross' or Marble Canyon spurge

Habit Herbs, usually biennial, occasionally annual, with taproot. Herbs, perennial, with deep stout rootstock.
Stems

erect or ascending, decumbent and often branched near base, 10–40 cm, glabrous.

erect, branched, densely clumped, previous year’s dead stems persistent, 25–45(–60) cm, glabrous, striate.

Leaves

petiole usually 5–10 mm, 0–1 mm distally;

blade usually oblanceolate to obovate, rarely ovate, 5–30 × 3–10 mm, base broadly attenuate, margins entire, apex usually obtuse to rounded, occasionally slightly retuse, surfaces glabrous;

venation pinnate, midvein prominent.

alternate, persisting, usually reflexed, occasionally spreading;

stipules 0.1–0.3 mm;

petiole 0.2–2.2 mm, glabrous;

blade narrowly ovate to lanceolate proximally, narrowly lanceolate, linear, or filiform distally, 10–32 × 0.5–6.5 mm, base cuneate, margins entire, apex acute, surfaces pilose when young, sparsely strigose or glabrous with age;

venation obscure, only midvein conspicuous.

Involucre

campanulate, 1.7–2.5 × 1.5–2.5 mm, glabrous;

glands 4, crescent-shaped; 0.6–1 × 0.8–1.5 mm;

horns divergent, 0.5–1.1 mm.

turbinate to campanulate, 2.2–3.7 × 1.5–2.5 mm, moderately strigose;

glands 5, dark green, reniform, 0.7–1.1 × 1–1.6 mm;

appendages white to pink, flabellate, 0.5–1.5 × 0.8–2.2 mm, dentate or erose.

Staminate flowers

9–15.

20–25.

Pistillate flowers

ovary glabrous;

styles 0.9–1.3 mm, 2-fid.

ovary strigose;

styles 1–1.3 mm, 2-fid at apex.

Capsules

ovoid-globose, 2.5–3.2 × 3 mm, slightly lobed;

cocci rounded to ± flattened, smooth, glabrous;

columella 1.5–2 mm.

subglobose, 2–3 × 4 mm, sparsely strigose;

columella 2–3 mm.

Seeds

white to gray, broadly oblong-elliptic to ovoid or nearly globose, 1.5–2 × 1.3–1.6 mm, strongly small-pitted;

caruncle irregularly winglike, conic, 0.6–1 × 0.7–0.9 mm.

gray-green to gray-brown, globose-ovoid, 1.8–2.2 × 1.2–1.6 mm, longitudinally pitted;

caruncle absent.

Cyathial

arrangement: terminal pleiochasial branches (2–)3(–4), 1–3+ times 2-branched;

pleiochasial bracts similar in shape and size to distal leaves;

dichasial bracts distinct to basally subconnate, not imbricate, widely ovate, rhombic, or reniform, base cordate, rarely slightly perfoliate, margins entire, apex obtuse to rounded, mucronulate;

axillary cymose branches 0–5.

Cyathia

peduncle 0.5–1 mm.

in terminal monochasia (thus appearing solitary at alternate nodes);

peduncle 0.5–2.5 (or 10–25) mm, glabrous or sparsely strigose.

Euphorbia commutata

Euphorbia aaron-rossii

Phenology Flowering and fruiting spring–summer. Flowering and fruiting spring–fall.
Habitat Bottomland and upland forests, bluffs and ledges, stream banks, glades, rarely fen margins. Sandy soils and dunes, occasionally rocky slopes, riparian areas.
Elevation 50–1000 m. (200–3300 ft.) 600–1300 m. (2000–4300 ft.)
Distribution
from FNA
AL; AR; FL; GA; IA; IL; IN; KY; LA; MD; MI; MO; MS; NC; OH; OK; PA; SC; TN; VA; WI; WV; ON
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ
[BONAP county map]
Discussion

Euphorbia aaron-rossii is restricted to the banks of the Colorado River in several small areas of the Grand and Marble canyons. The species is most closely related to E. strictior and E. wrightii, but due to its rarity, it has not been extensively studied.

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

Source FNA vol. 12, p. 300. FNA vol. 12, p. 242.
Parent taxa Euphorbiaceae > Euphorbia > subg. Esula Euphorbiaceae > Euphorbia > sect. Alectoroctonum
Sibling taxa
E. aaron-rossii, E. abramsiana, E. acuta, E. agraria, E. albomarginata, E. alta, E. angusta, E. antisyphilitica, E. arizonica, E. astyla, E. austrotexana, E. bicolor, E. bifurcata, E. bilobata, E. blodgettii, E. bombensis, E. brachycera, E. capitellata, E. carunculata, E. chaetocalyx, E. chamaesula, E. cinerascens, E. conferta, E. cordifolia, E. corollata, E. crenulata, E. cumulicola, E. cuphosperma, E. curtisii, E. cyathophora, E. cyparissias, E. davidii, E. deltoidea, E. dendroides, E. dentata, E. discoidalis, E. eriantha, E. exigua, E. exserta, E. exstipulata, E. falcata, E. fendleri, E. florida, E. floridana, E. garberi, E. georgiana, E. geyeri, E. glyptosperma, E. golondrina, E. gracillima, E. graminea, E. helioscopia, E. helleri, E. heterophylla, E. hexagona, E. hirta, E. hooveri, E. humistrata, E. hypericifolia, E. hyssopifolia, E. indivisa, E. innocua, E. inundata, E. ipecacuanhae, E. jaegeri, E. jejuna, E. laredana, E. lasiocarpa, E. lata, E. lathyris, E. longicruris, E. lurida, E. macropus, E. maculata, E. marginata, E. meganaesos, E. melanadenia, E. mendezii, E. mercurialina, E. mesembrianthemifolia, E. micromera, E. misera, E. missurica, E. myrsinites, E. nephradenia, E. nutans, E. oblongata, E. ocellata, E. ophthalmica, E. ouachitana, E. parishii, E. parryi, E. pediculifera, E. peplidion, E. peplus, E. perennans, E. pergamena, E. pinetorum, E. platyphyllos, E. platysperma, E. polycarpa, E. polygonifolia, E. polyphylla, E. porteriana, E. prostrata, E. pubentissima, E. purpurea, E. radians, E. rayturneri, E. revoluta, E. roemeriana, E. rosescens, E. schizoloba, E. serpens, E. serpillifolia, E. serrata, E. serrula, E. setiloba, E. simulans, E. spathulata, E. stictospora, E. strictior, E. telephioides, E. terracina, E. tetrapora, E. texana, E. theriaca, E. thymifolia, E. tithymaloides, E. trachysperma, E. trichotoma, E. vallis-mortae, E. velleriflora, E. vermiculata, E. villifera, E. virgata, E. wrightii, E. yaquiana
E. abramsiana, E. acuta, E. agraria, E. albomarginata, E. alta, E. angusta, E. antisyphilitica, E. arizonica, E. astyla, E. austrotexana, E. bicolor, E. bifurcata, E. bilobata, E. blodgettii, E. bombensis, E. brachycera, E. capitellata, E. carunculata, E. chaetocalyx, E. chamaesula, E. cinerascens, E. commutata, E. conferta, E. cordifolia, E. corollata, E. crenulata, E. cumulicola, E. cuphosperma, E. curtisii, E. cyathophora, E. cyparissias, E. davidii, E. deltoidea, E. dendroides, E. dentata, E. discoidalis, E. eriantha, E. exigua, E. exserta, E. exstipulata, E. falcata, E. fendleri, E. florida, E. floridana, E. garberi, E. georgiana, E. geyeri, E. glyptosperma, E. golondrina, E. gracillima, E. graminea, E. helioscopia, E. helleri, E. heterophylla, E. hexagona, E. hirta, E. hooveri, E. humistrata, E. hypericifolia, E. hyssopifolia, E. indivisa, E. innocua, E. inundata, E. ipecacuanhae, E. jaegeri, E. jejuna, E. laredana, E. lasiocarpa, E. lata, E. lathyris, E. longicruris, E. lurida, E. macropus, E. maculata, E. marginata, E. meganaesos, E. melanadenia, E. mendezii, E. mercurialina, E. mesembrianthemifolia, E. micromera, E. misera, E. missurica, E. myrsinites, E. nephradenia, E. nutans, E. oblongata, E. ocellata, E. ophthalmica, E. ouachitana, E. parishii, E. parryi, E. pediculifera, E. peplidion, E. peplus, E. perennans, E. pergamena, E. pinetorum, E. platyphyllos, E. platysperma, E. polycarpa, E. polygonifolia, E. polyphylla, E. porteriana, E. prostrata, E. pubentissima, E. purpurea, E. radians, E. rayturneri, E. revoluta, E. roemeriana, E. rosescens, E. schizoloba, E. serpens, E. serpillifolia, E. serrata, E. serrula, E. setiloba, E. simulans, E. spathulata, E. stictospora, E. strictior, E. telephioides, E. terracina, E. tetrapora, E. texana, E. theriaca, E. thymifolia, E. tithymaloides, E. trachysperma, E. trichotoma, E. vallis-mortae, E. velleriflora, E. vermiculata, E. villifera, E. virgata, E. wrightii, E. yaquiana
Synonyms Galarhoeus austrinus, G. commutatus, Tithymalus commutatus
Name authority Engelmann: in A. Gray, Manual ed. 2, 389. (1856) A. H. Holmgren & N. H. Holmgren: Brittonia 40: 357, figs. 1, 2. (1988)
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