Biosystematic studies onMaianthemum (Liliaceae-Polygonatae) |
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Authors: | Frederick H Utech Shoichi Kawano |
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Institution: | (1) Department of Biology, Washington University, 63110 St. Louis, Mo., USA;(2) Department of Biology, Toyama University, Gohuku, 930 Toyama;(3) Present address: Carnegie Museum of Natural History, Pittsburgh, Pa., USA |
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Abstract: | A similar floral vascular anatomy involving a constant dimerous, bicarpellate plan for each of the threeMaianthemum species is reported. All of the tepal, stamen and ovary traces are derived via repeated radial division of two pedicel bundles.
The four tepal and stamen traces are fusion products, as are the two dorsals. A third, smaller (vestigial) pedicel bundle
which continues unbranched and uninvolved into the ovary was observed in all three species. It could indicate a past reduction
from a trimerous, tricarpellate condition, and gives a basis for comparison to the closely related genusSmilacina. The gynoecial vasculature lacks peripheral laterals, septal axials and terminal cross-connections between the dorsal and
ventral supplies. The placentation is only apparently axile, since the two septa divide at the mid-ovary level. Consistently
the four co-lateral ovules which are anatropous and bitegmic are supplied by four free placentals. The placentals supplying
the two ovules of a given carpel have had a common origin in a single pedicel bundle. Raphides characterize post-fertilization
ovaries in all species. ADrusa-type of embyro sac formation shown forM. dilatatum corresponds with that known for the other species. An internal stigmoidal tissue system involving micropylar obturators extends
from the base of each locule through the hollow stylar canal. Temporal separation occurs between male and female meiosis (protandry),
and outbreeding is further promoted by terminal septal glands functioning as nectaries and the synchronized closure of the
common carpellary cavity by inter-digitating papillae on the inner septal margins.
This work was supported in part by the U.S.-Japan Cooperative Science Program Grant GF-41367, the Japanese Soceity for the
Promotion of Science and Grant-in-Aid No. 934053 from the Ministry of Education, Japan. |
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