Euphorbiaceae

Spurge Family, Euphorb Family

By Keith Haynes, M.D.

The Euphorbiaceae are a worldwide family of roughly 300 genera and 8000 species. This is the family of rubber trees, poinsettias, castor-beans, many Florida native species, and countless garden species and weeds. Spurges are extremely diverse yet united by having usually alternate leaves with stipules, unisexual (often monoecious) flowers, and three-parted ovaries topped with a three-branched (or six-branched) stigma. (Three-parted ovaries are unusual among Dicots.) The sap is usually milky. Some are succulent to the point of resembling cacti. Members of the genus Euphorbia (Poinsettia, Whitelace Euphorbia, Crown of Thorns, Candelabra-Cactus) have false flowers known as cyathia (sigh-AY-thee-ah, singular cyathium) made up of two or more colorful bracts that resemble petals surrounding clusters of numerous tiny unisexual flower so reduced as to be scarcely recognizable as individual flowers.

Key to Euphorbiaceae Important in South Florida Landscaping  (some data from BA1)

1A. Herbaceous annual, perennial or subshrub having white-margined leaves…Silver Fox Euphorbia (Euphorbia marginata)

1B. Vine with purple-violet “flowers” which are paired bracts resembling a bowtie…Bowtie Vine (Dalechampia dioscoreifolia)

1C. Plants otherwise…2

2. Plant a small native coastal tree or shrub having elliptic or lanceolate leaves; flowers with 4 sepals borne along the stem; fruits red, fuzzy, olive-sized…Guiana-Plum (Drypetes lateriflora) (unusual in cultivation)

2. Plants otherwise…3 (note 3 choices)

3A. Leaves opposite or very nearly so, the leaves (in most cultivated material) variegated with the undersides purple…Chinese-Croton (Excoecaria cochinchinensis)

3B. Leaves whorled; flowers (bracts) white, appearing in mid winter…Whitelace Euphorbia (Euphorbia leucocephala)

3C. Leaves alternate; flowers of varied colors, not limited to mid winter…4

4. Plants leafless or essentially so; branches resembling pencils…Penciltree (Euphorbia tirucalli)

4. Plants otherwise…5

5. Plants more or less succulent, with thorns or spines, the sap milky…6

5. Plants not succulent, thornless, the sap milky or clear…7

6. Plants resembling cacti, leafless or very nearly so, the thorns consisting of a pair of barbs…Candelabra-Cactus (Euphorbia lactea)

6. Plants usually leafy, the stipules thorny, basically paired and subdivided into multiple points; flowers (bracts) showy, usually red, sometimes yellow, creamy, pink, or bicolored…Crown of Thorns (Euphorbia milii)

7. Stem zigzagged; flowers (bracts) red, bilaterally symmetrical (shaped like a slipper)…Zigzag Plant (Euphorbia tithymaloides)

7. Stems straight or nearly so (not evenly zigzagged); flowers (or bracts) of variable colors, radially symmetrical…8

8. Bracts usually >1.5” long, usually bright red (or white or pink) and resembling the leaves in shape and outline…Poinsettia (Euphorbia pulcherrima)

8. Bracts absent or <1’ long, not colorful…9

9. Leaves palmately lobed (or palmately compound)…10

9. Leaves not palmately lobed and not palmately compound…11

10. Sap milky; leaflet margins entire (foliage may be variegated)…Manihot (Manihot esculenta)

10. Sap clear; leaflet margins toothed or lobed…Coral Plant (Jatropha multifida)

(Also consider Castorbean Ricinus communis--commonly encountered as a weed)

11. Leaf margins serrate or dentate…12

11. Leaf margins not toothy…14

12. Plants with long, bright red, showy, dangling inflorescences; foliage usually green…13

12. Plants otherwise, with the inflorescence dangling but small, thin and inconspicuous; foliage usually variegated with red, pink, or white…Copperleaf (Acalypha amentacea)

13. Plants mostly prostrate…Dwarf Chenille Plant (Acalypha pendula)

13. Plants shrubs…Chenille Plant (Acalypha hispida)

14. Leaves variegated; flowers inconspicuous…16

14. Leaf blades not variegated; flowers bright red…15

15. Leaves peltate, the base of the trunk swollen…Buddha-Belly Jatropha (Jatropha podagrica)

15. Leaves with the petiole attached at the edge, often with 2 or 3 (or 0) lobes, the base of the trunk not swollen…Red Jatropha (Jatropha integerrima)

16. Leaf blades thick, leathery, the colors glossy bright reds and yellows; shrubs not suckering…Croton (Codiaeum variegatum)

16. Leaf blades thin, the colors variable but flat-toned, reds, pinks, greens, and whites; shrubs suckering aggressively…Snow-on-the-Mountain (Breynia disticha)

Other plants listed in the manual include:

Cnidosculus chayamansa

Elaeophorbia drupifera

Gymnanthes lucida

Vernicia fordii