Rosaceae: hypanthial development and hypanthial ovaries

BOT 360F - Families of Vascular Plants
Spiraea flowers - 9752 Bytes Crataegus floral apex - 12281 Bytes
Perigyny - 13569 Bytes Epigyny - 16268 Bytes Crataegus flowers - 9425 Bytes
Crataegus hypanthial development (1) - 13334 Bytes Crataegus hypanthial development (2) - 13775 Bytes

A hypanthium, or floral cup (Judd et al. 1999, p. 56) results from growth beneath the common insertion base of the perianth and androecium primordia of the developing flower, as shown in the diagram at the left, above. When the region of intercalary growth extends beneath the gynoecial primordia (as shown in the diagram at the right, above), the resulting ovary can be referred to as a hypanthial ovary. Early development of the hypanthial ovary in Rosaceae subfamily Maloideae is illustrated above by dissections of developing hawthorn flowers. Hypanthial ovaries are also known as inferior ovaries, and the flowers in which they occur are referred to as epigynous. In the Maloideae, the fruits that develop from inferior ovaries are often referred to as pomes, even though compositionally they might equally be called berries or polypyrenous drupes.

First (leftmost) column: top, flowers of Spiraea salicifolia (Photo R. Presgrave, Royal Ontario Museum); bottom, development of hypanthium (green) through activity of an intercalary meristem (P, perianth primordia; A, androecial primordia; G, gynoecial primordia).

Second column: top, floral apex of Crataegus crus-galli following initiation of perianth (K, sepals; C, petals; Dickinson 1983); bottom, development of the hypanthial ovary (hypanthium in green) through activity of an intercalary meristem.

Third column: top, flowers of Crataegus crus-galli (Photo T. A. Dickinson, T. A. Dickinson); bottom, Crataegus crus-galli, development of the hypanthial ovary through activity of an intercalary meristem in the region marked D; white arrowheads indicate developing style (Dickinson 1983).

Fourth column: Crataegus crus-galli, further development of the hypanthial ovary; black arrowheads indicate developing style (to same scale as photo at left; Dickinson 1983).

Diagrams redrawn from Leins (1972) for Evans & Dickinson (1999). Photomicrographs shot in the lab of Dr Usher Posluszny, University of Guelph (Posluszny et al. 1980).


References

Dickinson, T. A. (1983). Crataegus crus-galli L. sensu lato in southern Ontario: phenotypic variation and variability in relation to reproductive behavior. Ph.D. thesis, Univ. of Western Ontario.

Evans, R. C. & T. A. Dickinson. 1999. Floral ontogeny and morphology in subfamily Spiraeoideae Endl. (Rosaceae). Int. J. .Plant Sci. 160(5): 981-1012.

Evans, R. C. & T. A. Dickinson. 2005. Floral ontogeny and morphology in Gillenia ("Spiraeoideae") and subfamily Maloideae C. Weber (Rosaceae). Int. J. Plant Sci. 166 (3): 427-447.

Leins, P. (1972). The carpel in the superior and inferior ovary. Ber. Deutsch. Bot. Ges. 85(7-9): 291-294.

Posluszny, U., Scott, M. G. & R. Sattler (1980). Revisions in the technique of epi-illumination light microscopy for the study of floral and vegetative apices. Can. J. Bot. 58: 2491-2495.


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