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COMPARATIVE REPRODUCTIVE BIOLOGY OF ACER PENSYLVANICUM AND A. SPICATUM (ACERACEAE)
Author(s) -
Sullivan Janet R.
Publication year - 1983
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1983.tb06431.x
Subject(s) - biology , pollen , ovule , pollinator , botany , pollination , aceraceae , gynoecium , outcrossing , apomixis , stamen , maple , ploidy , biochemistry , gene
Pollination mechanisms and floral features affecting reproduction were examined in two closely‐related species, Acer pensylvanicum and A. spicatum . Intra‐specific crossing experiments, studies of pollen stainability and ovule number, and observations of the flowers in the field revealed that neither species bears functionally hermaphroditic flowers. Three flower‐types were found in each species: staminate, pistillate, and a third type that is morphologically hermaphroditic. The latter form sheds viable pollen, but the pistil does not contain ovules. Pollen‐ovule ratios of both species are in the range of expectation for a facultatively xenogamous reproductive system. Outcrossing is accomplished by entomophily in both species. A variety of insects from several orders visit the flowers; however bees in the genus Andrena (Hymenoptera: Andrenidae), especially A. milwaukeensis , are considered the most important pollinators of both maple species because of their fidelity to Acer , their intrafloral behavior, and their ability to carry pollen. However, flies are the most abundant visitors to A. pensylvanicum . Apomixis is an important means of reproduction in A. spicatum . Although floral phenology of these maple species overlaps within a geographical region they were never found blooming simultaneously when growing together.