Flowering plant magnoliid (2%) clades. The remaining 5 clades contain a little over 250 species in total; i.e. less than 0.1% of flowering plant diversity, divided among 9 families. The 43 most-diverse of 443 families of flowering plants by species, in their APG circumscriptions, are Of these, the Orchidaceae, Poaceae, Cyperaceae, Araceae, Bromeliaceae, Arecaceae, and Iridaceae are monocot families; Piperaceae, Lauraceae, and Annonaceae are magnoliid dicots; the rest of the families are eudicots. Double fertilization refers to a process in which two sperm cells fertilize cells in the ovule. This process begins when a pollen grain adheres to the stigma of the
Flowering Locus C produce a number of generations during one summer ("summer-annual"), or (b) flower only after vernalization ("winter-annual" or "late-flowering"). This kind of variation can also be provided by variation in the "FRIGIDA" ("FRI") gene. Flowering Locus C Flowering Locus C ("FLC") is a MADS-box gene that in late-flowering ecotypes of the plant "Arabidopsis thaliana" is responsible for vernalization. In a new seedling "FLC" is expressed, which prevents flowering. Upon exposure to cold, less "FLC" is expressed (to a degree depending on the amount of cold), and flowering becomes possible. "FLC" is extensively regulated through epigenetic modifications and transcriptional control. The expression