Stomata in Platanus


Ontogeny and Classification of the Stomatal Complex of Platanus L.

by Brett D. (1979)Donald_Brett

Bedford College, University of London, UK

in Annals of Botany 44, 249-251,

The Platanus stoma was classified as ‘anomocytic’ by Metcalfe and Chalk (1950) but the regularity of the cell pattern led Baas (1969) to conclude that it did not fit into any of the categories originally recognized by Metcalfe and Chalk.
Krassilov (1973) also referred to the stomata as anomocytic but added: ‘Exceptional stomata with a pair of narrow paracytic subsidiary cells.’
Fryns-Claessens and Van Cotthem (1973) recognized the stomata described by Baas (loc. cit.) as belonging to the ‘cyclocytic’ type. According to Van Horn and Dilcher (1975) the organization of the mature stomatal complex is unique: ‘Each guard cell is slightly elevated in relation to the 2-4 lateral subsidiary cells which subtend it.’
There are no significant differences with respect to stomata between the four species of
Platanus examined by the present author (P. kerrii Gagn., P. occidentalis L., P. orientalis L. and
P.x hispanica Muench.). There is, however, considerable variation in the cell pattern of the stomata on an individual leaf ( as in many other plants of which the stomata can nevertheless be assigned to one of the common types).
The characteristic stomatal complex of Platanus has most often five (3 + 2) or six (3 + 3) lateral subsidiary cells; rarely eight (4+4) or none; and quite commonly from two to four or seven in the various possible permutations between the two guard cells.
It will be shown below that the larger characteristic stomata with from five to eight subsidiary cells are the first to be formed in the abaxial epidermis of the palmate leaves of P.x hispanica, and the guard cell mother cells which differentiate subsequently have fewer neighbouring protoderm cells: hence, at maturity, the later formed stomata have a different pattern of subsidiary cells and neighbouring cells.
There is no appropriate term in current classifications of mature stomatal types (Van
Cotthem, 1970) to describe the characteristic Platanus stomatal complex with its several
lateral subsidiary cells [Fig. 1(a)]. Some of the common variants, however, may be described as ‘paracytic’, with one subsidiary cell alongside each guard cell [Fig. 1(b)];
as ‘hemi-paracytic’ where there is only one subsidiary cell; as ‘anomocytic’ where
there are no subsidiary cells [Fig. I (c)].
To describe the Platanus type which has more than one subsidiary cell alongside one or both of the guard cells I introduce the new term ‘pleio-paracytic’ (these compound terms need not be hyphenated).

Available from: [accessed May 6, 2016].

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Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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