1	"Plants herbs; leaves opposite; involucral glands entire, with petaloid appendages"	"Euphorbia subg. Chamaesyce"
1	"Plants herbs, shrubs, or trees; leaves alternate and/or plants succulent; involucral glands entires, lobed, horned, or with fingerlike processes"	2
2	"Cyathia with 1 involucral gland; gland funnel-shaped; plants shrubs or annual herbs to 60 cm"	"Euphorbia subg. Poinsettia"
2	"Cyathia with 2-8 involucral glands or, if 1, plants fleshy perennial herbs less than 15 cm tall"	3
3	"Branches succulent, with horny pads or longitudinal ridges bearing spines (sometimes minute), at least on young growth; plants rarely reduced to a single column or spineless globose body"	"Euphorbia subg. Euphorbia"
3	"Branches herbaceous or woody or, if succulent, spineless; body, if globose, with leafy branches"	4
4	"Seeds with caruncle"	5
4	"Seeds without a caruncle"	7
5	"Seeds oblong-compressed, with flattened tubercles"	"Euphorbia subg. Eremophyton"
5	"Seeds ovoid, smooth"	6
6	"Plants leafy herbs, not fleshy"	"Euphorbia subg. Esula"
6	"Plants fleshy, cylindrical, with quickly deciduous leaves"	"Euphorbia subg. Tirucalli"
7	"Plants herbaceous, with fleshy, often swollen stems"	"Euphorbia subg. Eremophyton"
7	"Plants shrubs or trees with woody or semi-succulent branches"	8
8	"Cymes in umbels with ditomously branching rays; involucral glands lobed or pectinate"	"Euphorbia subg. Trichadenia"
8	"Cymes in umbels with simple, rarely branhing, rays or reduced to a single cyathiu; glands entire or, if lobed and pectinate, then rays simple"	9
9	"Glandular stipules not present; cyme bracts similar to the leaves"	"Euphorbia subg. Esula"
9	"Glandular stipules present, often minute; cyme-bracts different from the leaves, much smaller, scale-like, or conspicuous and creamy-white"	"Euphorbia subg. Lyciopsis"