MadSci Network: Botany

Re: What is the difference between cacti and euphorbias?

Date: Wed Aug 29 20:54:36 2001
Posted By: David Hershey, Faculty, Botany, NA
Area of science: Botany
ID: 998443223.Bt

Both the cactus family and euphorbia or spurge family are large diverse 
families. Some main differences are that cacti usually have clear, watery sap 
and many euphorbs have milky, sticky sap that is often toxic. Cactus spines 
occur in clusters of more than two on an aerole, an extremely short shoot. 
Euphorb spines are modified stipules and occur in pairs, and have no aeroles.

Flower structure also varies between the two families. The characteristic 
euphorb inflorescence is termed a cyathium, which appears as one flower but is 
several. Flowers lack petals. The female flower is elevated on a stalk and 
surrounded by tiny male flowers each consisting of just an anther. The flowers 
are then surrounded by cup-like leaves. In contrast to small flowers and 
inflorescence of euphorbs, cactus flowers are usually large single flowers with 
petals and many stamens. 

Cacti are native almost exlusively to dry areas of America while Euphorbia are 
native throughout the world in both wet and dry areas. Cactus-like euphorbs are 
found in Africa. The majority of cacti are succulents with fleshy stems adapted 
for water storage and photosynthesis and leaves reduced to spines or needles. 
Some euphorbs are succulents but many have broad leaves and are not succulent, 
such as poinsettia (Euphorbia pulcherrima), castor bean (Ricinis communis), 
snow-on-the-mountain (Euphorbia marginata), rubber tree (Hevea brasiliensis) 
and the houseplants croton (Codiaeum variegatum) and chenille plant (Acalypha 


Cacti ARE Succulents



Euphorb Houseplants

Euphorbiaceae - the Spurge Family



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