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Balkan spurge, egg-leaf spurge, oblong spurge

Roemer's spurge

Habit Herbs, perennial, with woody taproot. Herbs, annual, with taproot.
Stems

erect, unbranched or densely branching, 80 cm, often densely villous (especially young stems and pleiochasial branches).

erect, occasionally decumbent at base, branched, 15–30 cm, glabrous.

Leaves

petiole absent;

blade oblong to narrowly obovate or lanceolate, 15–70 × 6–25 mm, base rounded or truncate, margins finely serrulate, apex obtuse, mucronulate, surfaces glabrous;

venation inconspicuously pinnate, midvein prominent.

petiole 2–5 mm;

blade oblanceolate to obovate, 5–20 × 5–10 mm (larger leaves in distal portion of stem), base cuneate to attenuate, margins entire, apex rounded, surfaces glabrous;

venation pinnate.

Involucre

cupulate to slightly turbinate, 1.5–2.5 × 1.3–1.5 mm, glabrous;

glands 2–3, elliptic, 0.6–0.8 × 0.8–1.2 mm;

horns absent.

campanulate, 1.5–2 × 1–1.6 mm, glabrous;

glands 4, elliptic to trapezoidal, 0.4–0.6 × 0.7–1.2 mm;

horns slightly convergent, 0.1–0.3 mm.

Staminate flowers

15–40.

10–12.

Pistillate flowers

ovary glabrous;

styles 1.5–2 mm, 2-fid.

ovary glabrous;

styles 0.6–1 mm, 2-fid.

Capsules

globose, 3–4.5 × 3–4.5 mm, slightly 3-lobed;

cocci rounded, verrucose-tuberculate, glabrous;

columella 2.5–3.3 mm.

subglobose, 2–2.5 × 2.4–3 mm, slightly lobed;

cocci rounded, smooth, glabrous;

columella 1.5–1.8 mm.

Seeds

brown, ovoid, 2.4–2.6 × 1.3–2 mm, smooth, caruncle reniform, 0.2–0.3 × 0.8–0.9 mm.

brown, oblong-ovoid, 1.6–1.8 × 1.4–1.5 mm, with scattered, deep and broad pits;

caruncle conic, reniform, 0.3–0.4 × 0.4–0.6 mm.

Cyathial

arrangement: terminal pleiochasial branches 3–5, each 2–3 times 2–4-branched;

pleiochasial bracts ovate, similar in size to distal leaves;

dichasial bracts distinct, ovate to suborbiculate, base truncate or rounded, margins entire or finely denticulate, apex obtuse, sometimes mucronulate;

axillary cymose branches 0–4.

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

pleiochasial bracts ovate to oblong, similar in size to distal leaves;

dichasial bracts connate 1/2 length, reniform to semicircular, base truncate to perfoliate, margins entire, apex rounded to obtuse;

axillary cymose branches 0–3.

Cyathia

peduncle 1–5 mm.

peduncle 0–0.9 mm.

Euphorbia oblongata

Euphorbia roemeriana

Phenology Flowering and fruiting spring–fall. Flowering and fruiting spring.
Habitat Waste areas, disturbed sites, roadsides, fields, pastures. Rich calcareous soils, creek canyons.
Elevation 30–900 m. (100–3000 ft.) 100–300 m. (300–1000 ft.)
Distribution
from FNA
CA; OR; WA; s Europe [Introduced in North America]
[WildflowerSearch map]
[BONAP county map]
from FNA
TX
[BONAP county map]
Discussion

Euphorbia oblongata is listed as a noxious weed by the states of California, Oregon, and Washington.

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

D. S. Correll and M. C. Johnston (1970) suggested that Euphorbia roemeriana, which is restricted to the eastern part of the Edwards Plateau, is the southern counterpart of E. commutata, to which it is morphologically very similar. However, molecular phylogenetic analyses indicate that it is most closely related to E. austrotexana and E. longicruris (J. A. Peirson et al. 2014). Euphorbia roemeriana can be distinguished from E. commutata and several of the other small, annual species of subg. Esula by its consistently connate dichasial bracts.

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

Source FNA vol. 12, p. 305. FNA vol. 12, p. 308.
Parent taxa Euphorbiaceae > Euphorbia > subg. Esula Euphorbiaceae > Euphorbia > subg. Esula
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. 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. 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. 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. 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. 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 Tithymalus oblongatus Tithymalus roemerianus
Name authority Grisebach: Spic. Fl. Rumel. 1: 136. (1843) Scheele: Linnaea 22: 151. (1849)
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