This is the third dicot subclass. Unifying characters are: almost allherbaceous; flowers insect-pollinated, often showy; embryo curved around the nutritive tissue in the seed (hence old name Centrospermae for the subclass); most with betalain pigments (red and blue) rather than anthocyanins--exceptions are Caryophyllaceae and Molluginaceae.
 

1. Cactaceae--Succulent plants with areoles (modified buds or nodes) with leaves reduced to spines. Opuntia also with glochids. Ovary inferior, sunken into the stem. CA, CO, and A usually numerous, with some intergradation between CA and CO. Fruit a berry with parietal placentation.
 

2. Caryophyllaceae--Herbs with opposite leaves and swollen nodes, often with stipules or with transverse line connecting leaf bases. Flowers 5-merous except for G. Petals often notched. Fruit a capsule (often denticidal) with free-central placentation. Ex. Arenaria--Sandwort.
 

3. Polygonaceae--Herbs with alternate leaves and swollen nodes, many with sheathing stipules=ocrea. Usually one perianth whorl--calyx, which is often petalloid. Ex. Polygonum with fruit an achene.
 

Note: These are the three families we will look at closely in lab. Refer to lecture notes for field characters of the Amaranthaceae, Chenopodiaceae, Nyctaginaceae, etc. They are common members of the local flora and you will run into them in the field!

Return to the Caryophyllidae lab exercise

last modified July 23, 2007 by MDR