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  • Print publication year: 2005
  • Online publication date: June 2012

Chapter 17 - The leaf


Perspective: evolution of the leaf

All vascular plants except their most primitive ancestors are characterized by leaves (see Chapter 1). As the primary photosynthetic organs, leaves are of great significance not only to the plant but also to many other organisms, including humans, that rely on plants as a source of food. Botanists interested in the evolution of plant structures believe that leaves evolved in at least two ways, and in possibly five independent lines in vascular plants (see Niklas, 1997). The leaves of lycophytes are considered enations because they are thought to have evolved as simple outgrowths from stems. These leaves, often referred to as microphylls, are commonly small although those of some extinct taxa attained great lengths (up to 1 meter in some lepidodendrids). Like all microphylls, however, they were vascularized by only a single midvein. In seed plants and ferns (possibly also in sphenophytes) leaves are thought to represent evolutionarily modified lateral branch systems. This hypothesis (the telome hypothesis) is based on the fact that the earliest seed plant ancestors were leafless, but bore small lateral branch systems. The fossil evidence indicates that over time, three-dimensional branch systems became flattened and subsequently laminate. Seed plant leaves which, on average, are much larger, and much more complex than those of lycophytes in both gross morphology and internal structure, are often referred to as megaphylls. For more detailed discussions of the evolution of leaves see Steward and Rothwell (1993) and Taylor and Taylor (1993).

Andre, J. P., Catesson, A. M., and Liberman, M.. 1999. Characters and origin of vessels with heterogeneous structure in leaf and flower abscission zones. Can. J. Bot. 77: 253–261
Beck, C. B., Schmid, R., and Rothwell, G. W.. 1983. Stelar morphology and the primary vascular system of seed plants. Bot. Rev. 48: 691–815
Beebe, D. U. and Evert, R. F.. 1990. The morphology and anatomy of the leaf of Moricandia arvensis (L.) DC. (Brassicaceae). Bot. Gaz. 151: 184–203
Beerling, D. J. and Kelly, C. K.. 1996. Evolutionary comparative analyses of the relationship between leaf structure and function. New Phytol. 134: 35–51
BongardPierce, D. K., Evans, M. M. S., and Poethig, R. S.. 1996. Heteroblastic features of leaf anatomy in maize and their genetic regulation. Int. J. Plant Sci. 157: 331–340
Bowman, J. L. 2000. The YABBY gene family and abaxial cell fate. Curr. Opin. Plant Biol. 3: 17–22
Buisson, D. and Lee, D. W.. 1993. The developmental responses of papaya leaves to simulated canopy shade. Am. J. Bot. 80: 947–952
Burrows, G. E. 2001. Comparative anatomy of the photosynthetic organs of 39 xeromorphic species from subhumid New South Wales, Australia. Int. J. Plant Sci. 162: 411–430
Canny, M. J. 1993. Transfusion tissue of pine needles as a site of retrieval of solutes from the transpiration stream. New Phytol. 123: 227–232
Charlton, W. A. 1993. The rotated-lamina syndrome. I. Ulmaceae. Can. J. Bot. 71: 211–221
Charlton, W. A. 1997. The rotated-lamina syndrome. VII. Direct formation of lamina in the rotated position in Pterospermum (Sterculiaceae) and the appearance of hyper-rotation. Can. J. Bot. 75: 188–206
Cho, H. T. and Cosgrove, D. J.. 2000. Altered expession of expansin modulates leaf growth and pedicel abscission in Arabidopsis thaliana. Proc. Natl Acad. Sci. USA 97: 9783–9788
Dale, J. E. 1988. The control of leaf expansion. Annu. Rev. Plant Physiol. Plant Mol. Biol. 39: 267–295
DeMason, D. A. and Chawla, R.. 2004. Roles for auxin during morphogenesis of the compound leaves of pea (Pisum sativum). Planta 218: 435–448
Dengler, N. G. 1991. Patterns of leaf development in anisophyllous shoots. Can. J. Bot. 70: 676–691
Dengler, N. G. 1999. Anisophylly and dorsiventral shoot symmetry. Int. J. Plant Sci. 160: S67–S80
Dengler, N. G. and Kang, J.. 2001. Vascular patterning and leaf shape. Curr. Opin. Plant Biol. 4: 50–56
Dengler, N. G. and MacKay, L. B.. 1975. The leaf anatomy of beech, Fagus grandifolia. Can. J. Bot. 53: 2202–2211
Dengler, N. G. and Tsukaya, H.. 2001. Leaf morphogenesis in dicotyledons: current issues. Int. J. Plant Sci. 162: 459–464
Dengler, N. G., Dengler, R. E., Donnelly, P. M., and Hattersley, P. W.. 1994. Quantitative leaf anatomy of C3 and C4 grasses (Poaceae): bundle sheath and mesophyll surface area relationships. Ann. Bot. 73: 241–255
Dengler, N. G., Woodvine, M. A., Donnelly, P. M., and Dengler, R. E.. 1997. Formation of vascular pattern in developing leaves of the C4 grass Arundinella hirta. Int. J. Plant Sci. 158: 1–12
Donnelly, P. M., Bonetta, D., Tsukaya, H., Dengler, R. E., and Dengler, N. G.. 1999. Cell cycling during leaf development in Arabidopsis. Devel. Biol. 215: 407–419
Esau, K. 1977. Anatomy of Seed Plants, 2nd edn. New York: John Wiley and Sons
Evans, J. R. 1999. Leaf anatomy enables more equal access to light and CO2 between chloroplasts. New Phytol. 143: 93–104
Evert, R. F., Eschrich, W., and Heyser, W.. 1978. Leaf structure in relation to solute transport and phloem loading in Zea maysL. Planta 138: 279–294
Ferreira, J. F. S., Duke, S. O., and , K. C. Vaughn. 1998. Histochemical and immunological localization of tropane alkaloids in Erythroxylum coca var. coca and E. novogranatense. Int. J. Plant Sci. 159: 492–503
Fisher, D. G. 1989. Leaf structure of Cananga odorata (Annonaceae) in relation to the collection of photosynthate and phloem loading: morphology and anatomy. Can. J. Bot. 68: 354–363
Fisher, D. G. 1985. Morphology and anatomy of the leaf of Coleus blumei (Lamiaceae). Am. J. Bot. 72: 392–406
Fisher, D. G. 1991. Plasmodesmatal frequency and other structural aspects of assimilate collection and phloem loading in leaves of Sonchus oleraceus (Asteraceae), a species with minor vein transfer cells. Am. J. Bot. 78: 1549–1559
Fisher, J. B. and Rutishauser, R.. 1990. Leaves and epiphyllous shoots of Chisocheton (Meliaceae): a continuum of woody leaf and stem axes. Can. J. Bot. 68: 2316–2328
Fleming, A. J. 2002. The mechanism of leaf morphogenesis. Planta 216: 17–22
Fleming, A. J., Caderas, D., Wehrli, E., McQuenn-Mason, S., and Kuhlemeier, C.. 1999. Analysis of expansin-induced morphogenesis on the apical meristem of tomato. Planta 208: 166–174
Franceschi, V. R. and Giaquinta, R. T.. 1983a. The paraveinal mesophyll of soybean leaves in relation to assimilate transfer and compartmentation. I. Ultrastructure and histochemistry during vegetative development. Planta 157: 411–421
Franceschi, V. R. and Giaquinta, R. T. 1983b. Specialized cellular arrangements in legume leaves in relation to assimilate transport and compartmentation: comparison of the paraveinal mesophyll. Planta 159: 415–422
Fritz, E., Evert, R. F., and Heyser, W.. 1983. Microautoradiographic studies of phloem loading and transport in the leaf of Zea mays L. Planta 159: 193–206
Gerrath, J. M. and Lacroix, C. R.. 1997. Heteroblastic sequence and leaf development in Leea guineensis. Int. J. Plant Sci. 158: 747–756
Gould, K. S. 1993. Leaf heteroblasty in Pseudopanax crassifolius: functional significance of leaf morphology and anatomy. Ann. Bot. 71: 61–70
Green, P. B. 1999. Expression of pattern in plants: combining molecular and calculus-based biophysical paradigms. Am. J. Bot. 86: 1059–1076
Groom, P. K., Lamont, B. B., and Markey, A. S.. 1997. Influence of leaf type and plant age on leaf structure and sclerophylly in Hakea (Proteaceae). Austral. J. Bot. 45: 827–838
Gutschick, V. P. 1999. Biotic and abiotic consequences of differences in leaf structure. New Phytol. 143: 3–18
Hagemann, W. and Gleissberg, S.. 1996. Organogenic capacity of leaves: the significance of marginal blastozones in angiosperms. Plant Syst. Evol. 199: 121–152
Jung, G. and Wernicke, W.. 1990. Cell shaping and microtubules in developing mesophyll of wheat (Triticum aestivum L.). Protoplasma 153: 141–148
Kellogg, E. A. 1999. Phylogenetic aspects of the evolution of C4 photosynthesis. In , R. F. Sage and , R. K. Monson, eds., The Biology of C4 Synthesis. New York: Academic Press, pp. 411–422
Kenekordes, K. G., McCully, M. E., and Canny, M. J.. 1988. The occurrence of an extended bundle sheath system (paraveinal mesophyll) in the legumes. Can. J. Bot. 66: 94–100
Kerstetter, R. A. and Poethig, R. S.. 1998. The specification of leaf identity during shoot development. Annu. Rev. Cell Devel. Biol. 14: 373–398
Larkin, J. C., Young, N., Prigge, M., and Marks, D.. 1996. The control of trichome spacing and number in Arabidopsis. Development 122: 997–1005
Lawson, J. R. and Poethig, R. S.. 1995. Shoot development in plants: time for a change. Trends Genet. 11: 263–268
Lersten, N. R. 1990. Sieve tubes in foliar vein endings: review and quantitative survey of Rudbeckia laciniata (Asteraceae). Am. J. Bot. 77: 1132–1141
Lersten, N. R. and Curtis, J. D.. 1993. Paraveinal mesophyll in Calliandra tweedii and C. emarginata (Leguminosae; Mimosoideae). Am. J. Bot. 80: 561–568
Liljebjelke, K. A. and Franceschi, V. R.. 1991. Differentiation of mesophyll and paraveinal mesophyll in soybean leaf. Bot. Gaz. 152: 34–41
Lu, B., Villani, P. J., Watson, J. C., DeMason, D. A., and Cooke, T. J.. 1996. The control of pinna morphology in wildtype and mutant leaves of the garden pea (Pisum sativum L.). Int. J. Plant Sci. 157: 659–673
Lyndon, R. F. 1994. Control of organogenesis at the shoot apex. New Phytol. 128: 1–18
Martin, J. T. and Juniper, B. E.. 1970. The Cuticles of Plants. New York: St. Martin's Press
Martin, G., Josserant, S. A., Bornman, J. F., and Vogelmann, T. C.. 1989. Epidermal focusing and the light microenvironment within leaves of Medicago sativa. Physiol. Plant. 76: 485–492
Nasrulhaq-Boyce, A. and Duckett, J. G.. 1991. Dimorphic epidermal cell chloroplasts in the mesophyll-less leaves of an extreme-shade tropical fern, Teratophyllum rotundifoliatum (R. Bonap.) Holtt.: a light and electron microscope study. New Phytol. 119: 433–444
Nelson, T. and Dengler, N. G.. 1992. Photosynthetic tissue differentiation in C4 plants. Int. J. Plant Sci. 153: S93–S105
Nelson, T. and Dengler, N. G. 1997. Leaf vascular pattern formation. Plant Cell 9: 1121–1135
Niklas, K. J. 1997. The Evolutionary Biology of Plants. Chicago, IL: University of Chicago Press
Niklas, K. J. 1999. A mechanical perspective on foliage leaf form and function. New Phytol. 143: 19–31
Osborne, D. J. 1976. Auxin and ethylene and the control of cell growth. Identification of three classes of target cells. In Pilet, P., ed., Plant Growth Regulation. Berlin: Springer-Verlag, pp. 161–171
Osborne, D. J. and Sargent, J. A.. 1976a. The positional differentiation of ethylene responsive cells in rachis abscission zones in leaves of Sambucus nigra and their growth and ultrastructural changes at senescence and separation. Planta 130: 203–210
Osborne, D. J. and Sargent, J. A. 1976b. The positional differentiation of abscission zones during development of leaves of Sambucus nigra and the response of the cells to auxin and ethylene. Planta 132: 197–204
Panteris, E., Apostolakos, P., and Galatis, B.. 1993a. Microtubule organization, mesophyll cell morphogenesis, and intercellular space formation in Adiantum capillis-veneris leaflets. Protoplasma 172: 97–110
Panteris, E., Apostolakos, P., and Galatis, B. 1993b. Microtubules and morphogenesis in ordinary epidermal cells of Vigna sinensis leaves. Protoplasma 174: 91–100
Periasamy, K. 1962. Morphological and ontogenetic studies in palms. I. Development of the plicate condition in the palm-leaf. Phytomorphology 12: 54–64
Periasamy, K. 1965. Growth pattern of the leaves of Cocos nucifera and Borassus flabellifer after the initiation of placations. Austral. J. Bot. 13: 225–234
Poulson, M. E. and Vogelmann, T. C.. 1990. Epidermal focusing and effects upon photosynthetic light-harvesting in leaves of Oxalis. Plant Cell Environ. 13: 803–811
Press, M. C. 1999. The functional significance of leaf structure: a search for generalizations. New Phytol. 143: 213–219
Romberger, J. A., Hejnowicz, Z., and Hill, J. F.. 1993. Plant Structure: Function and Development. Berlin: Springer-Verlag
Russin, W. A. and Evert, R. F.. 1984. Studies on the leaf of Populus deltoides (Salicaceae): morphology and anatomy. Am. J. Bot. 71: 1398–1415
Seagull, R. W. 1989. The plant cytoskeleton. CRC Crit. Rev. Plant Sci. 8: 131–167
Shields, L. M. 1951a. Leaf xeromorphy in dicotyledon species from a gypsum sand deposit. Am. J. Bot. 38: 175–190
Shields, L. M. 1951b. The involution mechanism in leaves of certain xeric grasses. Phytomorphology 1: 225–241
Sinha, N. R. and Kellogg, E. A.. 1996. Parallelism and diversity in multiple origins of C4 photosynthesis in the grass family. Am. J. Bot. 83: 1458–1470
Soros, C. L. and Dengler, N. G.. 2001. Ontogenetic derivation and cell differentiation in photosynthetic tissues of C3 and C4 Cyperaceae. Am. J. Bot. 88: 992–1005
Steward, W. N. and G. W. Rothwell. 1993. Palaeobotany and the Evolution of Plants. Cambridge, UK: Cambridge University Press
Sussex, I. M. and Clutter, M. E.. 1960. A study of the effect of externally supplied sucrose on the morphology of excised fern leaves in vitro. Phytomorphology 10: 87–99
Taylor, J. E. and Whitelaw, C. A.. 2001. Signals in abscission. New Phytol. 151: 323–339
Taylor, J. E., Tucker, G. A., Lasslett, Y., et al. 1990. Polygalacturonase expression during leaf abscission of normal and transgenic tomato plants. Planta 183: 133–138
Taylor, T. M. and Taylor, E. L.. 1993. The Biology and Evolution of Fossil Plants. Englewood Cliffs, NJ: Prentice-Hall
Tomlinson, P. B. 1961. Anatomy of the Monocotyledons, vol. 2, Palmae. Oxford, UK: Clarendon Press
Troughton, J. and , L. A. Donaldson. 1972. Probing Plant Structure. Wellington, NZ: New Zealand Ministry of Research, Science and Technology
Waites, R. and Hudson, A.. 1995. Phantastica: a gene required for dorsoventrality of leaves in Antirrhinum majus. Development 121: 2143–2154
Wernicke, W., Günther, P., and Jung, G.. 1993. Microtubules and cell shaping in the mesophyll of Nigella damascena L. Protoplasma 173: 8–12
Further reading
Appleby, R. F. and Davies, W. J.. 1983. The structure and orientation of guard cells in plants showing stomatal responses to changing vapour pressure difference. Ann. Bot. 52: 459–468
Black, C. C. and Mollenhauer, H. H.. 1971. Structure and distribution of chloroplasts and other organelles in leaves with various rates of photosynthesis. Plant Physiol. 47: 15–23
Brown, W. V. 1958. Leaf anatomy in grass systematics. Bot. Gaz. 119: 170–178
Campbell, R. 1972. Electron microsopy of the development of needles of Pinus nigra var. maritima. Ann. Bot. 36: 711–720
Cronshaw, J., Lucas, W. J., and Giaquinta, R. T. (eds.) Phloem Transport. New York: Alan R. Liss
Cross, G. L. 1940. Development of the foliage leaves of Taxodium distichum. Am. J. Bot. 27: 471–482
Cross, G. L. 1942. Structure of the apical meristem and development of the foliage leaves of Cunninghamia lanceolata. Am. J. Bot. 29: 288–301
DeMason, D. A. and Villani, P. J.. 2001. Genetic control of leaf development in Pea (Pisum sativum). Int. J. Plant Sci. 162: 493–511
Edwards, G. and Walker, D.. 1983. C3, C4: Mechanisms, and Cellular Environmental Regulation, of Photosynthesis. Oxford, UK: Blackwell
Erickson, R. O. and Michelini, F. J.. 1957. The plastochron index. Am. J. Bot. 44: 297–305
Esau, K. 1965. Vascular Differentiation in Plants. New York: Holt, Rinehart, and Winston
Eschrich, W., Burchardt, R., and Essiamah, S.. 1989. The induction of sun and shade leaves of the European beech (Fagus sylvatica L.): anatomical studies. Trees 3: 4–10
Fisher, D. G. 1986. Ultrastructure, plasmodesmatal frequency, and solute concentration in green areas of variegated Coleus blumei Benth. leaves. Planta 169: 141–152
Fleming, A. J. 2003. The molecular regulation of leaf form. Plant Biol. 5: 341–349
Foster, A. S. 1936. Leaf differentiation in angiosperms. Bot. Rev. 2: 349–372
Foster, A. S. 1952. Foliar venation in angiosperms from an ontogenetic standpoint. Am. J. Bot. 39: 752–766
Franck, D. H. 1979. Development of vein pattern in leaves of Ostrya virginiana (Betulaceae). Bot. Gaz. 140: 77–83
Gambles, R. L. and Dengler, R. E.. 1982a. The anatomy of the leaf of red pine, Pinus resinosa. I. Nonvascular tissues. Can. J. Bot. 60: 2788–2803
Gambles, R. L. and Dengler, R. E. 1982b. The anatomy of the leaf of red pine, Pinus resinosa. II. Vascular tissues. Can. J. Bot. 60: 2804–2824
Ghouse, A. K. M. and Yunus, M.. 1974. Transfusion tissue in the leaves of Cunninghamia lanceolata (Lambert) Hooker (Taxodiaceae). Bot. J. Linn. Soc. 69: 147–151
Griffith, M. M. 1957. Foliar ontogeny in Podocarpus macrophyllus, with special reference to the transfusion tissue. Am. J. Bot. 44: 705–715
Hall, L. N. and Langdale, J. A.. 1996. Molecular genetics of cellular differentiation in leaves. New Phytol. 132: 533–553
Harris, W. M. 1971. Ultrastructural observations on the mesophyll cells of pine leaves. Can. J. Bot. 49: 1107–1109
Jarvis, P. G. and Mansfield, T. A. (eds.) 1981. Stomatal Physiology. Cambridge, UK: Cambridge University Press
Jones, C. S. and Watson, M. A.. 2001. Heteroblasty and preformation in mayapple, Podophyllum peltatum (Berberidaceae): developmental flexibility and morphological constraint. Am. J. Bot. 88: 1340–1358
Kaplan, D. R. 1970. Comparative foliar histogenesis in Acorus calamus and its bearing on the phyllode theory of monocotyledonous leaves. Am. J. Bot. 57: 331–361
Kaplan, D. R. 1973. The monocotyledons: their evolution and comparative biology. VII. The problem of leaf morphology and evolution in the monocotyledons. Q. Rev. Biol. 48: 437–457
Kaplan, D. R. 1984. Alternative modes of organogenesis in higher plants. In White, R. A. and Dickison, W. C., eds., Contemporary Problems in Plant Anatomy. New York: Academic Press, pp. 261–300
Kaplan, D. R. 2001. Fundamental concepts of leaf morphology and morphogenesis: a contribution to the interpretation of molecular genetric mutants. Int. J. Plant Sci. 162: 465–474
Kaplan, D. R., Dengler, N. G., and Dengler, R. E.. 1982. The mechanism of plication inception in palm leaves: histogenic observations on the palmate leaf of Raphis excelsa. Can. J. Bot. 60: 2999–3016
Kausik, S. B. and Bhattacharya, S. S.. 1977. Comparative foliar anatomy of selected gymnosperms: leaf structure in relation to leaf form in Coniferales and Taxales. Phytomorphology 27: 146–160
Kessler, S., Kim, M., Pham, T., Weber, N., and Sinha, N.. 2001. Mutations altering leaf morphology in tomato. Int. J. Plant Sci. 162: 475–492
Laetsch, W. M. 1974. The C4 syndrome: a structural analysis. Annu. Rev. Plant Physiol. 25: 27–52
Lee, C. L. 1952. The anatomy and ontogeny of the leaf of Dacrydium taxoides. Am. J. Bot. 39: 393–398
Lersten, N. R. and Curtis, J. D.. 2001. Idioblasts and other unusual internal foliar secretory structures in Scrophulariaceae. Plant Syst. Evol. 227: 63–73
Lersten, N. R. and Horner, H. T.. 2000. Calcium oxalate crystal types and trends in their distribution patterns in leaves of Prunus (Rosacaeae: Prunoideae). Plant Syst. Evol. 224: 83–96
Maksymowych, R. 1973. Analysis of Leaf Development. Cambridge, UK: Cambridge University Press
Mansfield, T. A., Hetherington, A. M., and Atkinson, C. J.. 1990. Some current aspects of stomatal physiology. Annu. Rev. Plant Physiol. Plant Mol. Biol. 41: 55–75
Marcotrigiano, M. 2001. Genetic mosaics and the analysis of leaf development. Int. J. Plant Sci. 162: 513–525
Merrill, E. K. 1979. Comparison of ontogeny of three types of leaf architecture in Sorbus L. (Rosaceae). Bot. Gaz. 140: 328–337
Metcalfe, C. R. and Chalk, L.. 1950. Anatomy of the Dicotyledons, 2 vols. Oxford UK: Clarendon Press
Millington, W. F. and Gunckel, J. E.. 1950. Structure and development of the vegetative shoot tip of Liriodendron tulipifera L. Am. J. Bot. 37: 326–335
Nelson, T. and Langdale, J. A.. 1989. Patterns of leaf development in C4 plants. Plant Cell 1: 3–13
Njoku, E. 1971. The effect of sugars and applied chemicals on heteroblastic development in Ipomoea purpurea grown in aseptic culture. Am. J. Bot. 58: 61–64
Pate, J. S. and Gunning, B. E. S.. 1969. Vascular transfer cells in angiosperm leaves: a taxonomic and morphological survey. Protoplasma 68: 135–156
Philpott, J. 1953. A blade tissue study of leaves of forty-seven species of Ficus. Bot. Gaz. 115: 15–35
Pray, T. R. 1955a. Foliar venation of angiosperms. II. Histogenesis of the venation of Liriodendron. Am. J. Bot. 42: 18–27
Pray, T. R. 1955b. Foliar venation of angiosperms. IV. Histogenesis of the venation of Hosta. Am. J. Bot. 42: 698–706
Pray, T. R. 1963. Origin of vein endings in angiosperm leaves. Phytomorphology 13: 60–81
Romberger, J. A. 1963. Meristems, growth, and development in woody plants. US Dept. Agric. Tech. Bull. 1293: 1–214
Russin, W. A. and Evert, R. F.. 1985. Studies on the leaf of Populus deltoides (Salicaceae): ultrastructure, plasmodesmatal frequency, and solute concentrations. Am. J. Bot. 72: 1232–1247
Steeves, T. A. and Sussex, I. M.. 1989. Patterns in Plant Development, 2nd edn. Cambridge, UK: Cambridge University Press
Stevens, R. A. and Martin, E. S.. 1978. A new ontogenetic classification of stomatal types. Bot. J. Linn. Soc. 77: 53–64
Williams, R. F. 1975. The Shoot Apex and Leaf Growth: A Study in Quantitative Biology. London: Cambridge University Press
Wylie, R. B. 1939. Relations between tissue organization and vein distribution in dicotyledon leaves. Am. J. Bot. 26: 219–225
Wylie, R. B. 1951. Principles of foliar organization shown by sun–shade leaves from ten species of deciduous dicotyledonous trees. Am. J. Bot. 38: 355–361
Wylie, R. B. 1952. The bundle sheath extension in leaves of dicotyledons. Am. J. Bot. 39: 645–651
Ziegler, H. 1987. The evolution of stomata. In Zeiger, E., Farquhar, G. D., and Cowan, I. R., eds., Stomatal Function. Stanford, CA: Stanford University Press, pp. 29–57