evolution and systematics of Onagraceae: leaf anatomy

Using a collection of liquid-preserved vegetative shoots representing all 17 genera of Onagraceae, I investigated the cross-sectional histology of mature leaves. The study focussed on a search for systematically useful and diagnostic features as well as on the determination of possible trends of spe...

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Bibliographic Details
Published in:Annals of the Missouri Botanical Garden 1982, Vol.69 (4), p.770-803
Main Author: Keating, R.C
Format: Article
Language:English
Subjects:
Anatomy
Animal cuticle
Cults
Genera
Ground tissue
Mesophyll
Phloem
plant anatomy
plant morphology
plant taxonomy
Ravens
Trichomes
Xylem
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Summary:Using a collection of liquid-preserved vegetative shoots representing all 17 genera of Onagraceae, I investigated the cross-sectional histology of mature leaves. The study focussed on a search for systematically useful and diagnostic features as well as on the determination of possible trends of specialization of leaf features. Exclusively dorsiventral-leaved species are found in Ludwigia, Hauya, Fuchsia, Circaea, and Lopezia. Leaves of these genera also have the most prominent midrib structure. The most generalized anatomy including the presence of extraxylary fibers and diverse calcium oxalate crystal structure is found in Fuchsia, Ludwigia, and Hauya. The other twelve genera, which belong to the tribes Epilobieae and Onagreae, show a variety of leaf specializations including xeromorphic isobilateral structure, small midribs with small midveins, the absence of extraxylary fibers, the absence of druses and styloid crystals, and a poorly differentiated mesophyll. On the basis of correlations with data from wood anatomy, pollen morphology, reproductive biology, and biogeography, I hypothesize that the Onagraceae leaves show a general reduction in leaf complexity. Leaf anatomy by itself is not diagnostic for those genera with reduced structure but it may be distinctive in the genera with more complex structure such as Fuchsia, Ludwigia, and Hauya.
ISSN:0026-6493
2162-4372
DOI:10.2307/2398996