BLUMEA2I (1973) 381 —411 Epidermalleaf characters of the Winteraceae J.M. Bongers Rijksherbarium, Leiden, Netherlands Contents Summary 381 Introduction 382 Materials and methods 382 A survey of the cuticular characters in Winteraceae Introduction 383 Thickness of the cuticle 383 Alveolar material 3 84 Unspecialized cells 384 Venation 386 Stomatal complex 387 Cork warts and 'glands' 387 Anatomical descriptions 388 Variation of the cuticular characters within Drimys piperita Introduction 393 Epidermal variability within entities of Drimys piperita 394 Variation of the characters in Drimys piperita as a whole 397 Discussions The value ofthe characters used 399 Taxonomic implications 400 The entities ; interrelations ofthe n Drimys piperita 402 Physiological significance ofstomatal occlusions 402 Acknowledgements 403 References 404 Summary in cuticular Leaf epidermal features (mostly studied macerations) of 146 specimens, belonging to c. 33 Winteraceae in is species of all the 6 genera of the are described detail. Typical for most representatives the of alveolar material of cutinaceous nature the cuticle and occurrence overlying proper, usually occluding the stomata.Special attention ispaid to the appearance, distribution and significance ofthis alveolar material. The taxonomic value of the characters described is discussed. All show with in number of leaf genera an overlap one or more genera a varying epidermal characters, absolute the level absent. distinct so diagnostic characters at genus are It is also impossible to recognize of and Belliolum within the leaf ofBubbia. groups genera. Exospermum are entirely epidermalrange Drimys section Tasmannia and Bubbia perrieri take the most isolated positions within the family. shows is Drimys piperita an enormous range of variation, which further analysed using 85 specimens belonging to 38 of the 39 entities recognized by Vink. Of 12 entities more than one specimen was studied, affording the conclusion that in most entities the cuticular features are fairly constant, though some entities are very variable and certain characters are almost always variable at the level of the entity. For Drimys piperita as a whole a number of characters (shape and relative size of the stomata, shape of epidermalcells over midrib, undulations of anticlinal flanges, subdivisions of subsidiary cells) are mutually correlated and show, moreover, positive trends ofcorrelation with the usual habitat ofthe entities. The glandular structures, for D. are described for the first time. typical piperita, BLUMEA VOL. No. 382 XXI, 2, 1973 Introduction The cuticles of some representatives of the Wititeraceae have received the attention of several authors feature in the past. The most striking usually reported for the family is the of the stomatal presence plugs occluding apertures (Wulff, 1898; Ziegenspeck, 1941; Bailey & Nast, 1944b, Bondeson; 1952; Vink, 1970). Occhioni & Occhioni (1947) and Rao (1939) apparently overlooked these structures in their studies of Drimys brasiliensis and Drimys winteri respectively. Wulff and Ziegenspeck considered the plugs to be of a & discussed the these waxy composition. Bailey Nast more elaborately nature of plugs, and cutinaceous suggested a composition, though admitting to present no full-proof evidence. Vink clearly distinguished between waxy and cutinaceous alveolar occlusions, both present in Winteraceae. The ofthe considered be the family Winteraceae, usually to primitive amongst Dicotyle- The and Vink dons, comprises 6 genera. revisions of Smith (1943 a+b) (1970) have been used the basis for this anatomical study. The as genus Drimys accordingly comprises 2 with from South sections: Drimys 4 species in America, ranging Cape Horn to Mexico with (Smith, 1943 a) and section Tasmannia 5 species (according to Vink's recent revision, in which he subdivided D. piperita in 37 'entities'; Smith recognized 36 species), ranging from Malesia Austraha. Pseudowintera Zealand to occurs with 3 species in New (Vink). The from Caledonia Smith genus Exospermum New comprises two species according to (1943b). Vink considers these to be one species (unpublished private communication). New Bubbia is composed of 30 species in Smith's treatment (1943 b), occurring in Guinea, New Caledonia, Australia, andLord Howe I. Morerecently Capuron (1963) described one from has in New more species: Bubbia perrieri Madagascar. Belliolum 4 species Caledonia and the Solomon record with 6 all 4 in Is. (Smith, 1943b). Zygogynum is on species, confined to New Caledonia (Smith, 1943 b). This study was carried out in the first place to elucidate the peculiar structures reported on by a number of authors, and in the second place to make a more or less comprehensive the variation the characters the different survey of range of of epidermal in taxa of the Winteraceae in general, and in Drimys piperita in particular. Moreover, it was hoped that such a study would be of some use for the discussion of affinities within the family. Besides it was thought to be of some help for paleobotanists in the identification of fossil plant remains (cf. Jahnichen, 1959). MATERIALS AND METHODS One each the mature leaf was selected from of 146 herbarium specimens used for this All material from the for of study. is Rijksherbarium at Leiden, except the type specimens Zygogynum baillonii (Pancher s.n.) and Bubbia perrieri (Perrier de la Bathie 10150), which were obtained from the Paris Herbarium. Of Drimys winteri fresh leaves were pickled from cultivated a specimen at Royal Botanic Gardens at Kew. All material used for cuticular macerations was boiled in water. Parts from the middle the macerated of lamina, including midrib and leaf margin, were overnight in a mixture of the equal volumes of 20% hydrogen peroxide and glacial acetic acid at 60°C; cuticles obtained were stained in a solution of Sudan IV in alcohol 70%, and finally mounted in glycerin-jelly. From sections of the lamina 17 leaves also transverse were made through the middle and the distal of the with a Reichert of the part petiole, sliding microtome. Part sections with of for was stained a mixture safranin and haematoxylin permanent euparal mounts, the stained Sudan remainder was with IV and mounted in glycerin-jelly. J. M. BONGERS : Epidermis of Winteraceae 383 leaves For Scanning Electron Microscope studies fragments of 62 were extracted with in in ether for one hour at room temperatureand subsequently rinsed fresh ether order to with remove any wax. The leaffragments were coated carbon and gold. The distribution ofthe the The number of specimens over different genera is as follows. species studied is indicated between brackets behind the generic name. Macerations S.E.M. Transverse sections I.1. Drimys Tasmatttiia 8 sect. Tasmannia (5) 89 33 (D. piperita) (85) (29) (8) sect. Drimys (4) 8 IO10 II 2. Pseudowintera (3) 4 4 I1 3. Exospermum (1) I1 IIII 4. Belliolum (2) 2 2 I1 5.5. Bubbia (18) 36 IO10 4 6. 6. Zygogynum (6) 6 3 II Collection of the numbers ofthe herbariumspecimens studied are listed at the end generic descriptions, and in table I for Drimys piperita. Stomatalsizes were measured at iooo x magnification, using an eye-piece micrometer; were made leaf. 25 measurements per A SURVEY OF THE CUTICULAR CHARACTERS IN WINTERACEAE Introduction used this taken also Most of the terms in descriptive part are from Stace (1965), who about cuticles. the is gave more general information Usually leaf cuticle two-layered. The innerlayer: the cuticular layer, consists of a cellulose framework, incrusted with cutin; cuticle The the outer layer: the proper, is mainly composed of cutin. cuticular layer may in the smooth. and that appear granular light microscope or Bailey Nast (1944b) reported in Winteraceae alveolar be the cuticle The a third, layer may present overlying proper. alveolar is result the layer not homogeneous and usually has a white colour as a of presence ofair in the interstices. This layer is insoluble in boiling water or ether and stains positively with Sudan IV. Therefore, the composition is apparently cutinaceous. The birefringence decisive reported by Bailey & Nast is, however, no proof for the cutinaceous nature (see Martin and Juniper, 1970). In cuticular preparations the features of the underlying cuticle proper and the cuticular layer are often obscured by this alveolar material. also be as the outermost either of the cuticle Wax may present layer, on top proper, if the latter ofthe of or overlying the alveolar layer is present. Because ephemeral nature herbarium the have wax on specimens (depending on drying procedures etc.) wax deposits been considered in this section Tasmannia & not study, except for Drimys (phot. 27 28). Thickness ofthe cuticle Although macerated cuticular preparations yield no detailed information about the of the thickness ofthe cuticle, one gains animpression its relative thickness during micro- technical procedures. Some cuticles are rather stiff and stain deeply with Sudan IV, others delicate and take stain. these extremes of are very hardly up any Between very thick and thin cuticles all intermediates encountered. Transverse sections very are were made of all the 17 specimens representing six genera, so that some absolute figures on thickness available. The from 2 to for the abaxial side has been subdivided are range 25 /im 384 BLUMEA VOL. XXI, No. 2, 1973 follows: (very) thin, 2 medium thickness, 10 thick, 11—20 as —5 fim; 6— /urn; /um; very These terms used the The cuticle the adaxial thick, over 20 jum. are in descriptions. on