Contains 25 accepted taxa overall.
Characteristics
In the modern sense, Euphorbia s.l. is a large genus of ca. 2000 species characterized by its cyathium (an involucre of clustered, reduced male and female flowers). Euphorbia s.l. includes other traditionally recognized genera such as Chamaesyce, Pedilanthus, and Poinsettia (see Horn et al. 2012; Yang et al. 2012). The Florida species formerly placed in the genus Chamaesyce are now reclassified under Euphorbia subg. Chamaesyce sect. Anisophyllum subsect. Hypericifoliae. The Florida species formerly placed in the genus Poinsettia are now reclassified under Euphorbia subg. Chamaesyce sect. Poinsettia subsect. Stormieae. The former genus Pedilanthus is reclassified under Euphorbia subg. Euphorbia sect. Crepidaria. Many species have a toxic sap, and toxicity from exposure to poinsettia has been reported (D'Arcy 1974).
Classification
Citation
EUPHORBIA Linnaeus, Sp. Pl. 450. 1753.
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TYPE: Euphorbia antiquorum Linnaeus 1753. Typified by Millspaugh, Publ. Field Columbian Mus., Bot. Ser. 2: 306. 1909.
Species
| Scientific Name | Common Name | Herbarium Specimens | Status | Photos |
|---|---|---|---|---|
| Euphorbia bombensis | Southern Seaside Spurge, Dixie Sandmat | |||
| Euphorbia commutata | Woodland Spurge, Tinted Spurg | |||
| Euphorbia cordifolia | Heartleaf Sandmat | |||
| Euphorbia corollata | Eastern Flowering Spurge | |||
| Euphorbia curtisii | White Sandhills Spurge, Curtis's Spurge | |||
| Euphorbia cyathophora | Painted Leaf, Fire-on-the-mountain | |||
| Euphorbia cyparissias | Cypress Spurge, Graveyard Spurge | |||
| Euphorbia dentata | Painted Leaf, Wild Poinsettia, Toothed Spurge | |||
| Euphorbia discoidalis | Summer Spurge | |||
| Euphorbia exserta | Maroon Sandhills Spurge, Coastal Sand Spurge | |||
| Euphorbia graminea | Grassleaf Spurge | |||
| Euphorbia helioscopia | Wartweed | |||
| Euphorbia heterophylla | Fiddler’s Spurge, Mexican Fireplant | |||
| Euphorbia hirta | Pillpod Sandmat | |||
| Euphorbia hypericifolia | Graceful Sandmat | |||
| Euphorbia hyssopifolia | Hyssopleaf Sandmat | |||
| Euphorbia ipecacuanhae | Carolina Ipecac | |||
| Euphorbia lathyris | Caper Spurge, Myrtle Spurge, Mole Plant | |||
| Euphorbia maculata | Milk-purslane, Spotted Spurge | |||
| Euphorbia marginata | Snow-on-the-mountain | |||
| Euphorbia nutans | Eyebane | |||
| Euphorbia obtusata | Woodland Spurge | |||
| Euphorbia polygonifolia | Northern Seaside Spurge | |||
| Euphorbia prostrata | Prostrate Sandmat | |||
| Euphorbia serpens |
Identification Key
1. Stems spiny (sect. Goniostema, subg. Euphorbia)
1. Stems without spines
2
2. Trees; stems succulent, with few or no leaves (sect. Tirucalli, subg. Euphorbia)
2. Herbs to shrubs; stems succulent or not, generally leafy (if not leafy, then stem ziz-zag)
3
3. Stems zig-zag and succulent; involucres strongly zygomorphic, spurred and forming tube that encloses glands (sect. Crepidaria, subg. Euphorbia, formerly of genus Pedilanthus)
3. Stems succulent or not, not zig-zag; involucres mostly actinomorphic, not spurred
4
4. Leaves alternate to opposite, mostly symmetric at the base, the larger blades usually >2 cm long (if smaller, then some leaves alternate); stipules at base of petiole or absent
5
4. Leaves all opposite, usually conspicuously asymmetric especially near the base, the blades <3.5 cm long, <1.5 cm wide; stipules interpetiolar (sect. Anisophyllum, subg. Chamaesyce, formerly of genus Chamaesyce)
5. Leaf blades subtending inflorescence often pale green, white, pink, or red at the base or throughout the blade (sect. Poinsettia, subg. Chamaesyce, formerly of genus Poinsettia)
5. Leaf blades subtending inflorescence uniform in color (or with white margins in E. marginata)
6
6. Stems often relatively thin, gracile, 0.5-3 mm thick, often with relatively long internodes exceeding the leaves; stipules mostly minute and glanduliform, rarely subulate-filiform; (2-)5(-10) glands per cyathium, the glands usually with petaloid appendages (sect. Alectoroctonum, subg. Chamaesyce)
6. Stems relatively thick, stout, 2-5 mm thick, often with relatively short internodes shorter than the leaves; 4-5(-7) glands per cyathium, the glands without petaloid appendages or with horn-like appendages
7
7. Larger leaf blades >2 cm long; stipules minute to elongate, glandular; seeds ecarunculate (sect. Nummulariopsis, subg. Euphorbia)
7. Larger leaf blades <4 cm long; stipules usually absent; seeds usually carunculate
8
8. Leaf blade serrulate, venation conspicuous (sect. Helioscopia, subg. Esula)
8. Leaf blade entire, venation obscure (sect. Paralias, subg. Esula)
1. Key A (sect. Anisophyllum, subg. Chamaesyce) Leaves mostly ascending and imbricate, the blade often involute; usually restricted to shoreline habitats
1. Leaves mostly spreading and not imbricate, the blade flat, revolute, to involute; habitats various, from inland to shoreline habitats
2
2. Larger leaf blades usually 10-45 mm long, 4-15 mm wide, generally elliptic to rhombic, typically with evident lateral basal veins
3
2. Larger leaf blades 2-10 mm long, 2-5 mm wide, generally elliptic to ovate, lateral basal veins usually obscure or absent
9
3. Ovary and fruit pubescent
4
3. Ovary and fruit glabrous
7
4. Leaf blades mostly entire to roughened, teeth inconspicuous; cyathia solitary or in small, cymose clusters at distal nodes, on congested, axillary branches, or at branch tips
4. Leaf blades mostly conspicuously serrate to dentate; cyathia in capitate glomerules (with reduced, bractlike leaves subtending cyathia)
5
5. Stems pilose to tomentose; stipules distinct when young, connate into deltate scales when older, often with dark glands along margins or at base; styles 0.6–0.9 mm; seeds plumply ovoid, 0.7–0.8 mm wide, dark reddish brown to almost black
5. Stems usually both strigillose and hirsute; stipules distinct or connate only at base, deltate, subulate, or linear- or filiform-subulate, without dark glands along margins or at base; styles 0.1–0.6 mm; seeds narrowly ovoid or ovoid-oblong, 0.5–0.7 mm wide, not dark reddish brown to almost black
6
6. Glomerules of cyathia terminal or axillary, axillary glomerules sessile or at tips of elongated, leafless stalks; petaloid gland appendages white to pink, flabellate, subcircular, or transversely oblong, rarely absent, (0–)0.1–0.6 × (0–)0.1–0.7 mm
6. Glomerules of cyathia terminal on main stems or on short, leafy, axillary branches with reduced, bractlike leaves; petaloid gland appendages absent or white to pink, forming thin rim around edge of gland or oblong, 0.1–0.2 × 0.1–0.3 mm
7. Stems sparsely to moderately pilose to villous or with short, incurved hairs, pubescence often concentrated at nodes and distally (hairs occasionally in 2 bands along opposite sides of stem); leaf blades usually sparsely to moderately pilose, especially toward base, sometimes glabrous; seeds finely and irregularly wrinkled or with indistinct shallow, rounded cross ridges
7. Stems glabrous, sparsely to densely pilose, or pilose-crinkled proximally, usually glabrous distally; leaf blades glabrous or sparsely pilose toward base; seeds with prominent transverse ridges, coarsely and inconspicuously pitted-reticulate, or with shallow irregular depressions alternating with low, smooth ridges
8
8. Stipules 1.5-2.2 mm long, longer than wide; capsules 1-1.5 mm long or wide; seeds 0.9-1.1 mm long, ca. 0.5 mm wide
8. Stipules 0.5-1 mm long, usually wider than long; capsules 1.5-1.8 mm long or wide; seeds 1-1.4 mm long, 0.7-1.1 mm wide
9. Leaf blades mostly deltate to ovate, rarely elliptic, often cordate at the base, often revolute, usually 1-1.5 times longer than wide; restricted to pine rocklands
10
9. Leaf blades mostly oblong, elliptic, narrowly ovate, to oblate-orbicular, mostly rounded, cuneate, to truncate at the base, flat to revolute, usually 1.5-5.5 times longer than wide (or 1-2 times longer than wide and occasionally cordate at the base in E. serpens); habitats various including sandy soils, disturbed areas, and pine rocklands
13
10. Leaves and stems villous-hirsute, hairs straight and spreading, to 0.7 mm long; leaf blades silver-green
10. Leaves and stems villous, canescent, to glabrate, hairs appressed, uncinate, or irregularly twisted, to 0.5 mm long; leaf blades green to silver-green
11
11. Leaves and stems glabrous or very sparsely hairy, hairs 0.1–0.2 mm, appressed, uncinate; leaf blades adaxially bright green
11. Leaves and stems canescent or villous, hairs either less than 0.1 mm or 0.2–0.5 mm, uncinate or irregularly twisted; leaf blades green or silver-green
12
12. Leaves and stems villous, hairs uncinate or irregularly twisted, 0.2–0.5 mm; leaf blades green
12. Leaves and stems canescent, hairs less than 0.1 mm; leaf blades silver-green
13. Ovary and fruit pubescent
14
13. Ovary and fruit glabrous
22
14. Petaloid gland appendages of a cyathium strongly unequal, often one pair >2 times as large as the other pair
15
14. Petaloid gland appendages of a cyathium subequal or scarcely unequal, appendages inconspicuous or absent
17
15. Stem hairs mostly spreading and exserted, pilose to hirsute; petaloid appendages pink to reddish
15. Stem hairs mostly appressed, ascending, curled, or short, strigose, sericeous, to tomentulose; petaloid appendages white to pink
16
16. Leaf blade surface puberulent, strigose, to sericeous; cyathial gland oblong to reniform; petaloid appendages 0.3-1 mm long, 0.8-1.6 mm wide; capsules well exserted from involucre at maturity; seeds with 3 or 4 transverse sulci alternating with low transverse ridges
16. Leaf blade surface glabrous to sparsely tomentulose; cyathial gland elliptic to oval; petaloid appendages to 0.4 mm long or wide; capsules scarcely exserted from involucre, base often remaining inside the involucre and splitting one side of it during maturity; seeds with 4 low transverse ridges, but not sulcate
17. Root rather thick, to 5 mm wide; stems ascending to ascending-erect, becoming woody towards the base, younger stems usually pubescent on all sides
17. Root slender to 3 mm wide, stems prostrate, decumbent, to ascending, herbaceous to somewhat woody towards the base, younger stems pubescent on the upper side and glabrate below
18
18. Stems often rooting at the nodes
18. Stems usually without adventitious roots
19
19. Capsules usually with pubescence concentrated along keels or toward base, often glabrous between keels
20
19. Capsules mostly evenly hairy or pubescence at least not concentrated only along keels and base, not glabrous between keels
21
20. Plant hairs to 0.6 mm long; petioles, leaf blade abaxial surfaces, ovaries, and capsules glabrous or sparsely sericeous, pilose, or villous; seeds reddish brown to orange or gray-pink, almost smooth or with faint transverse ridges
20. Plant hairs to 0.3 mm long; petioles, leaf blade abaxial surfaces, ovaries, and capsules crisped-villous to glabrate; seeds white but with barely concealed brown surface beneath, with sharp transverse ridges;
21. Leaf blades usually entire or the teeth obscure; styles clavate, bifid at the apex, 0.3-0.4 mm long; capsules well exserted from involucre at maturity; seeds 1-1.2 mm long
21. Leaf blades typically conspicuously toothed; styles slender, bifid half the length, 0.4-0.6 mm long; capsules scarcely exserted from involucre, base often remaining inside involucre and splitting one side of it during maturity; seeds 0.7-0.9 mm long
22. Stipules (at least those of upper side of stem) connate, forming deltate, ligulate, or ovate scales
23
22. Stipules usually distinct, occasionally connate basally, not forming conspicuous, deltate, ligulate, or ovate scales
25
23. Stems erect to ascending
24
23. Stems prostrate to decumbent
26
24. Leaf blades (2.2)3.0-6.0(-8.3) times longer than wide, narrowly lanceolate to linear elliptic, 1-veined, glands of the cyathia narrower than or equal to the gland appendages in radial dimension; cyathia, glands, gland appendages, capsules, and stems light to deep red to purple; mainland southern Florida
24. Leaf blades 0.01-3.0(3.5) times longer than wide, ovate to lanceolate, 1- to 3-veined, glands of the cyathia radially wider than the gland appendages; cyathia, glands, gland appendages, capsules, and stems light green to light red; mainland southern Florida, or Florida Keys
25
25. Leaf blades (1.0)1.8-2.5(3.5) times longer than wide, 1-veined to weakly 3-veined, the apex acute; glands of the cyathia 0.4-0.6 mm wide; Florida Keys
25. Leaves ovate-elliptic, 1.0-1.7(2) times longer than wide, 3-veined, the apex obtuse to rounded; glands of the cyathia 0.6-1.0 mm wide; mainland southern Florida
26. Stems prostrate to decumbent; petaloid gland appendages unequal (pair near sinus lunate to oblong, 0.1–0.2 × 0.1–0.3 mm, distal margins entire, crenulate, or irregularly sinuate, other pair rudimentary, 0–0.1 × 0.1–0.3 mm, distal margins crenulate or entire)
26. Stems prostrate; petaloid gland appendages equal, forming narrow rim at edge of gland, 0.1–0.2 × 0.2–0.3 mm, distal margins entire or crenulate
27. Leaf blades toothed
27. Leaf blades mostly entire or the teeth obscure
28
28. Seeds (2–)2.2–2.8 mm, weakly dorsiventrally compressed in cross section
28. Seeds 0.7–2.1 mm, terete to bluntly sub- or 3-angled in cross section
29
29. Leaf blades 1-2 times longer than wide, generally broadly elliptic to ovate-oblong, often cordate at the base, generally not involutely folded along the midrib; styles 0.5-0.8 mm long
29. Leaf blades 1.5-3.5 times longer than wide, generally elliptic and rounded to subcordate at the base, often involutely folded along the midrib; styles 0.2-0.3 mm long
30
30. Leaf blades oblong or elliptic-oblong, 2-3 mm wide; petaloid gland appendages (0–)0.1–0.5(–0.7) mm; seeds 1.5-1.9 mm long
30. Leaf blades narrowly elliptic to lanceolate, 1-2 mm wide; petaloid gland appendages 0.1–0.2 mm, often rudimentary; seeds 1–1.3 mm
1. Key B (sect. Poinsettia) Leaves mostly opposite to subopposite, occasionally some alternate, the blade margins mostly regularly crenate-dentate; caruncle of the seed 0.4-0.6 mm wide
1. Leaves primarily alternate, occasionally a few opposite near the base, the blade margins entire, subentire, lobate, or obscurely serrulate; caruncle of the seed absent or to 0.1 mm wide
2
2. Leaf blades 0.8-7 mm wide, linear (very rarely lobed), lateral veins not evident; cyathium often with purplish colors throughout, rarely without; glands (1-)3-5 per cyathium, reddish or purplish (rarely green)
2. Leaf blades 2-100 mm wide, linear to obovate, sometimes lobed, lateral veins usually evident; cyathium generally lacking purplish colors; gland 1(-2) per cyathium, yellow-green
3
3. Leaf blades subtending the inflorescence (pleiochasial bracts) white to red at the base to throughout, rarely only green; cyathial gland elliptic to oblong; seed rounded in cross-section
3. Leaf blades subtending the inflorescence (pleiochasial bracts) white to green at the base; cyathial gland circular; seed angular in cross-section
1. Key C (sect. Alectoroctonum, subg. Chamaesyce) Short-lived plants mostly of disturbed sites, the taproot grading into the main stem
2
1. Perennial plants mostly of woodlands, the main root thicker than the main stems
3
2. Usually some proximal leaf blades toothed; inflorescence bracts without conspicuous white margins
2. Leaf blades entire; bracts below inflorescence with conspicuous white margins or nearly wholly white
3. Leaves usually numerous and overlapping along the whole stem below the inflorescence branches of mature plants; leaves 0.5-2 mm wide
3. Often at least some portion of the main stem conspicuously with few to no leaves below the inflorescence branches of mature plants; larger leaves 2-30 mm wide
4
4. Peduncles 10–50(–70) mm; petaloid gland appendages absent or inconspicuous, 0–0.2 mm wide
4. Peduncles 1–17(-40) mm; petaloid gland appendages usually apparent, 0.3–3.5(–4.5) mm wide
4
5. Petaloid gland appendages 0.3–0.6 mm long
5. Petaloid gland appendages (0.5–)1–3.5 mm long
6
6. Stem usually densely puberulent to sericeous, rarely glabrous; leaf blade 1-4 mm wide; seed 2 mm long
6. Stem usually glabrous, rarely villous; leaf blade 2-30 mm wide; seed 2.2-2.4 mm long
1. Key D (sect. Nummulariopsis, subg. Euphorbia) Larger leaf blades usually >9 mm wide, the blade apex rounded to obtuse (sometimes with a mucro)
2
1. Larger leaf blades usually <14 mm wide, the blade apex acute
3
2. Involucre 2.4–3.6 × 2.5–3.6 mm; cyathial glands yellow-green, sometimes with a light red margin; styles 3.3–3.6 mm, connate 1/2 length
2. Involucre 1.3–2.3 × 1.6–2.5 mm; cyathial glands dark purple; styles (1–)1.3–1.5 mm, connate 1/4 length
3. Peduncles (except for that of 1st cyathium at base of pleiochasia) 2–5 mm long; cyathial lobes green; seeds depressed-globose, wider than long
3. Peduncles 6–24 mm long; cyathial lobes reddish along the apex; seeds ovoid-globose, longer than wide
4
4. Leaf blades narrowly linear, linear, or narrowly linear-lanceolate, 1.5–3.5(–4.5) mm wide, length 15–20(–50) times width
4. Leaf blades usually linear to narrowly elliptic or narrowly lanceolate, rarely oblanceolate, (3–)4–14(–15) mm wide, length usually 5–10(–25) times width
Genus Synonyms
| Synonym | Full Citation | Basionym | Type |
|---|---|---|---|
| No synonyms found. | |||