Monoecious annual, biennial or perennial herbs, shrubs or trees, sometimes succulent. Milky latex present. Stipules usually present. Leaves mostly alternate, sometimes opposite or whorled. Inflorescence composed of cyathia in simple, dichotomous or umbellate terminal cymes; bracts paired, often leaf-like, sometimes brightly coloured. Cyathia with (1-)4-5(-8) glands around the rim alternating with 5 fringed lobes. Male flowers in 5 groups separated by fringed membranes, bracteolate. Female flower subsessile or with the pedicel elongating or reflexed in fruit. Ovary 3-locular. Styles 3, partly united. Fruit a dehiscent capsule, usually 3-lobed.

Euphorbia L.:
Argentina (South America)
Brazil (South America)
Canada (North America)
Chile (South America)
Costa Rica (Mesoamerica)
French Guiana (South America)
Guyana (South America)
Honduras (Mesoamerica)
Mexico (Mesoamerica)
Paraguay (South America)
Suriname (South America)
Uruguay (South America)
Venezuela (South America)
Caribbean (Caribbean)
United States (North America)

Foodplant / gall
Heterodera cacti causes gall of cysted root of Euphorbia (succulent spp)

Foodplant / open feeder
larva of Aphthona atrocaerulea grazes on leaf of Euphorbia

Foodplant / open feeder
larva of Aphthona euphorbiae grazes on leaf of Euphorbia

Foodplant / open feeder
larva of Aphthona melancholica grazes on leaf of Euphorbia

Foodplant / gall
larva of Bayeria capitigena causes gall of shoot tip of Euphorbia
Other: sole host/prey

Foodplant / open feeder
adult of Cryptocephalus moraei grazes on live flower of Euphorbia
Remarks: season: 5-9

Foodplant / sap sucker
nymph of Dicranocephalus agilis sucks sap of Euphorbia

Foodplant / parasite
sporangium of Peronospora euphorbiae parasitises live Euphorbia

Foodplant / spot causer
Xanthomonas axonopodis pv. poinsettiicola causes spots on live leaf of Euphorbia

Waxy coating protects from heat and drought: euphorbia
 

The stems of euphorbias protect from heat and drought via their hard waxy surface.

     
  "On the ground around them grow numerous fat, spiny leafless plants that any non-botanist could be forgiven for calling -- without hesitation and even perhaps a certain amount of pride in his expertise -- cacti. Only if they are in flower might you suspect that they are not. Then a botanist would notice that the numbers of petals and anthers are quite different from those of cacti. These are euphorbias, members of one of the largest of all families of flowering plants with over seven thousand species. In Europe, its common representatives are dog's mercury and spurge. In South America, euphorbias grow into trees and shrubs, among them the rubber tree and the manioc plant. In African forests, its members include the castor oil bush. And in African deserts they become cacti look-alikes…The cactus family is, in fact, exclusively American, with hundreds of different species growing in deserts from Canada to Chile. The reason that members of these two families resemble one another so closely is that similar conditions of heat and drought have stimulated the same physical response. Both abandon their leaves at an early stage, since these inevitably lose a great deal of water, and both carry out their photosynthesis under the hard waxy surface of their stems which are green with chlorophyll. Both store water in a bloated pillar-like trunk. And both defend that water from robbers by armouring their trunks with sharp spines." (Attenborough 1995:272-275)
  Learn more about this functional adaptation.