Exine Reduction in Underwater Flowering Callitriche
No Thumbnail Available
Authors
Philbrick, Tom
Osborn, J.M.
Issue Date
1994-10-01T00:00:00-07:00
Item Type
Degree Name
Academic Department
Advisor
item.page.dc.subject.keywords
Keyword
Buy Link
Abstract
Both aerial and underwater pollination systems (hypohydrophily) occur in Callitriche (Callitrichaceae), and as such the genus can serve as a model system in which to probe questions concerning the evolution of hypohydrophily from aerial pollination systems. Evidence from scanning and transmission electron microscopy reveals strikingly different exine thickness in the pollen of four aerially flowering species (C. heterophylla var. bolanderi, C. marginata, C. peploides, and C. stagnalis), which have a distinct sexine layer (0.55—1.1 μm thick), in comparison with that of the hypohydrophilous C. hermaphroditica. The exine of the latter species is rudimentary.