Subclass Caryophyllidae is made up of only 3 orders, 14 families and about 11,000 species.  The large, diverse Order Caryophyllales includes about 90% of the species and also carries the relatively distinct set of features that mark the Subclass.  These include:
 

• anthocyanin pigments typical of most angiosperms are lacking in most families of the Caryophyllales and replaced by a class of pigments, betalains, that are found only in this Order (and some fungi)

• the Order is marked by a suite of unusual embryological features.  The nutritive tissue, for instance, found in the seeds of most Caryophyllales is not endosperm.  It is derived from sporophytic (diploid) tissue and known as perisperm.  Also, the embryo tends to occupy a peripheral position in the seed, which often produces a characteristic 'beaked' (protrusion of the radical) asymmetry:

• the perianth tends to be uniseriate via apetaly but often showy via petaloid sepals
• and the placentation pattern if often basal or free central thereby tending to place the ovules in a central position within the ovary - the archaic term 'Centrospermae' denotes this tendency

Patterns of relationship, as defined by Cronquist, within the Subclass and its largest Order:

  Redrawn from A. Cronquist - Evolution and Classification of Flowering Plants, 2nd ed.

Information provided by: http://www.csdl.tamu.edu