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have microphylls, as in all extant species there is only a single vascular trace in each leaf. These leaves are narrow because the width of the blade is limited by the distance water can efficiently diffuse cell-to-cell from the central vascular strand to the margin of the leaf. Despite their name,
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The simplistic evolutionary models, however, do not correspond well to evolutionary relationships. Some genera of ferns display complex leaves that are attached to the pseudostele by an outgrowth of the vascular bundle, leaving no leaf gap. Horsetails
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While the simple definitions (microphylls: one vein, macrophylls: more than one) can still be used in modern botany, the evolutionary history is harder to decipher.
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This article is about the classification based on leaf vasculature. For the terms "Microphyll" and "Megaphyll" as classifications of leaf size, see
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58:. Leaf gaps are small areas above the node of some leaves where there is no vascular tissue, as it has all been diverted to the leaf.
131:). The fossil record appears to display these traits in this order, but this may be a coincidence, as the record is incomplete. The
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proposes instead that both microphylls and megaphylls originated by the reduction; microphylls by reduction of a single
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WN Stewart & GW Rothwell (1993) Palaeobotany and the evolution of plants. 2nd edition. Cambridge
University Press.
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record, and few such plants exist today. In the classical concept of a microphyll, the leaf vein emerges from the
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119:). Outgrowths of the protostele (the central vasculature) later emerged towards the enations (as in
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Qiu, Y.L.; Palmer, J.D. (1999). "Phylogeny of early land plants: insights from genes and genomes".
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162:, which has a (simple) protostele, and enations devoid of vascular tissue. Some species of
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bear needles with only one vein, but these evolved later from plants with complex leaves.
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125:), and eventually continued to grow fully into the leaf to form the mid-vein (such as in
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with one single, unbranched leaf vein. Plants with microphyll leaves occur early in the
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have a single vascular trace that terminates at the base of the enations. Consequently,
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267:"The Science of Plant Morphology: Definition, History, and Role in Modern Biology"
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Taylor, T.N.; Taylor, E.L. (1993). "The biology and evolution of fossil plants".
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branch, and megaphylls by evolution from branched portions of a telome.
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How the Earth Turned Green: A Brief 3.8-Billion-Year
History of Plants
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of megaphyllous organisms or have evolved more than once.
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of microphyll evolution posits that small outgrowths, or
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can reach 25 centimetres in length, and the extinct
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74:Microphylls contain a single vascular trace.
321:Morphology and evolution of vascular plants
204:Megaphylls have a complex network of veins.
87:microphylls are not always small: those of
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319:Gifford E.M. & Foster, A.S. (1989).
185:It is not clear whether leaf gaps are a
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221:has secondarily lost leaves, and bears
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178:). However, genetic analysis has shown
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99:bore microphylls up to 78 cm long.
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156:An interesting case is that of
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323:. WH Freeman, New York, USA.
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271:American Journal of Botany
170:was long thought to be a "
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237:Vegetation classification
397:Trends in Plant Science
376:Cite journal requires
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265:Kaplan, D.R. (2001).
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54:without leaving a
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431:Categories
243:References
84:horsetails
80:clubmosses
60:Megaphylls
52:protostele
33:microphyll
146:Equisetum
103:Evolution
37:lycophyll
29:evolution
18:Leaf size
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231:See also
223:enations
218:Psilotum
180:Psilotum
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164:Psilotum
159:Psilotum
113:enations
56:leaf gap
293:3558347
90:Isoëtes
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137:telome
48:fossil
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41:plant
413:PMID
382:help
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107:The
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