Taxonomy
of Flowering Plants - LECTURE
NOTES - Fall, 1998
Hugh
D. Wilson - rm. 306,
Butler Hall
5/7 October 1998
The Caryophyllidae
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.
Our survey of the group will include:
Caryophyllales
Phytolaccaceae
Cactaceae
Chenopodiaceae
(and Amaranthaceae)
Caryophyllaceae
Polygonales
Polygonaceae
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