Cronquist, Arthur New York Botanical Garden, New York, New York.
Barkley, Theodore M. Division of Biology, Kansas State University, Manhattan, Kansas.
Last reviewed:December 2019
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A relatively small subclass of the class Magnoliopsida (dicotyledons) of the division Magnoliophyta (Angiospermae), the flowering plants, consisting of 3 orders, 14 families and about 11,000 species. They have mostly trinucleate pollen and ovules with two integuments (bitegmic) and a nucellus that is more than one cell thick (crassinucellate). Also, the ovules are often distorted by unequal growth so that the micropyle is brought near the funiculus and the chalazal end (campylotropous), or half inverted so the funiculus is attached near the middle (amphitropous) and these are usually borne on a free-central or basal placenta.
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