Pollen morphology of some European Rosaceae Tj. Reitsma (.Botanical Museum and Herbarium, Utrecht) {received February 17th, 1966) Abstract In this attention preliminary investigation was paid to pollen morphology of West-European species of the Rosaceae. Some new terms were used like fastigium, endocingulus etc. The terminology of Iversen and Troels-Smith has been followed in addition to improvements by Erdtman. A key is given to the types and subtypes for the use of pollen analytical investigators. Sanguisorba officinalis appeared to be always 3-colporate and not 6-colporate. 1. Introduction It well that different the is known types of pollen grains are found in Rosaceae. Faegri and Iversen (1964) mention some in their key to the N.W. Potentilla European pollen types, e.g. Crataegus type, type, Geum From there be type. pollen analytical investigations appear to more present types than the three above. The object was to form pollen morphological types, which are easily distinguishable from each other by constant differences. These types have been worked up into a key for the use of pollen analytical investigators. Within the types it was sometimes possible to give a key to the included is made genera or species. In these keys use of less constant and distinctive differences such as the length, the shape etc. 2. Materials and methods 2.1. Flowers Pollen grains were obtained from herbarium material at the Botanical Museum and Herbarium of Utrecht, and from freshly collected flowers. Only flowers which just bloomed or are about to bloom are useful. 2.2. Treatment of the pollen grains fresh treated the Pollen grains from flowers were with acetolysis- method of Erdtman (1943). If only a little material was present and this is especially so in the case of herbariummaterial, the micro-method described by Punt (1962) has been used. 2.3. Preservation For the preservation of the grains the paraffin-method with the has the improvements by Punt (1962) been used, viz. use of a granule ofclay to support the cover-glass. This prevents large grains from being compressed. 290 POLLEN MORPHOLOGY OF SOME EUROPEAN ROSACEAE 291 2.4. Microscopes The pollen grains have been studied with a Leitz Ortholux binocular ol 10 and (obj. pi. apo 100/1.32, oc. periplan x) an Olympus phase- contrast microscope. This microscope was found very useful in detecting the configuration of the structural elements. 2.5. Drawings The been in that pollen grains have drawn such a manner in one characters time. drawing as many as possible are to be seen at the same Each drawing therefore is midway between scheme and a photo- graphical reproduction. The pollen grains have been drawn to scale, without a camera lucida or other drawing instruments. The enlargment is 2000 X except Mespilus viz. 1000 X. 2.6. Photographs Leitz Microphotographs were made with a Orthomatcamera and 63 Ortholux microscope apochr. obj. X 40, X and an eyepiece X 10. 3. Terminology In principle the terminology of Iversen and Troels-Smith (1950) has been followed, although in addition improvements by Erdtman have been used (see also Punt, 1962). At the same time some terms have been used, which need a new or altered description: Aperture (Faegri and Iversen, 1950) A thinning or missing of a part of the sexine or nexine CoLUMELLAE INDEX-C.I. The ratio between the maximum height of the exine to the maximum height of the columellae Costa pi. costae (Faegri and Iversen, 1950) Thickenings of the nexine Costae colpi: Thickened nexine below the edge of colpi Costae endocinguli: Thickened edges of the endocingulus Costae endocolpi: Thickened edges of the endocolpus Costae endopori: Thickened edges of the endoporus Costae pori: Thickened nexine below the edge of pori Ectoaperture (Van Campo, 1958) the A thinning or a missing of a part of sexine e.g. colpus, porus Endoaperture (Van Campo, 1958) A thinning or a missing of a part of the nexine Endocingulus Endoaperture, forming a band round the equator, of which the diameter is perpendicular to the axis of the ectoaperture. Endocolpus (Zagwijn, 1963) Endoaperture, of which one of the axes of the aperture is perpendi- cular to an axis of the ectoaperture. Length: breadth > 2 292 TJ. REITSMA Endoporus (Zagwijn, 1963) of of Endoaperture, which one the axes of the aperture is perpendi- cular axis of the breadth to an ectoaperture. Length: > 2 Membrana granulata (Erdtman, 1952) Colpus or porus membrane (= nexine) with some scattered structural elements. Membrana nudata (Erdtman, 1952) membrane = without structural elements Colpus or porus ( nexine) Nexine (Erdtman, 1948) The inner, non-sculptured part of the exine Sexine (Erdtman, 1948) The outer sculptured part of the exine Fastigium pi. Fastigia (= Atrium Punt, 1962) Cavity, inside colporate grains, caused by the separation of the nexine and the domed sexine in the area of the endoapertures. Punt (1962) named this an atrium. This term, however, has been Thomson used by Pflug in a publication by and Pflug (1953) for triporate Tertiary pollen grains. Consequently it is not advis- able to use this term here. The shapes of the pollen grains in polar and equatorial view are described according to the system of Kuyl, Muller and Waterbolk (1955). The system of Erdtman (1952), which is based on the relation between the polar axis and the equatorial axis {P'-E) in equatorial view, is also used. The length of the longest axis has been indicated in the description. This which be either the the measurement, may equatorial or polar of the axis, is an exact indication of the size pollen grain. Key to the types 1 Pollen a grain with striae 2 b Pollen grain without striae, that is psilate, echinate, scabrate, or only with phase contrast microscope striate 7 2 a Pollen grain operculate 3 b Pollen grain not operculate 4 3 Pollen costae Potcntilla a grain without colpi type b Pollen grain with costae colpi Rosa gallica type 4a Striae indistinct, intrastriate 5 b Striae distinct, extrastriate 6 5 a Pollen grain with costae colpi Rubus idaeus type b Pollen grain without costae colpi Crataegus type 6 a Pollen grain with tectum Geum type b Pollen grain with tectum perforatum Mespilus type 7 a Pollen grain without structural elements on tectum 8 elements b Pollen grains with structural on tectum 12 8 a Pollen grain operculate 9 b Pollen grain not operculate 10 C.I. with costae Rosa canina 9 a > 4, pollen grain colpi type b C.I. < 3, pollen grain without costae colpi Sanguisorba type 10 C.I. < columellae in than those at the a 3, intercolpium higher poles Alchemilla type b C.I. >4, columellae in intercolpium as high as those at the poles 11 POLLEN MORPHOLOGY OF SOME EUROPEAN ROSACEAE 293 Pollen with Rubus idaeus 11 a grain costae colpi type b Pollen grain without costae colpi Crataegus type a Structural elements small: . 12 scabrae; endocolpus . Filipendula type b elements Structural large: echinae, gemmae, or verrucae; endoporus Rubus chamaemorus type 4. Results 4.1 General . Rosaceae of The pollen grains of the studied show a number types, which can be distinguished clearly from each other. However, they all represent variations on the same theme. That and They all are tricolporate. both tricolpate stephanocol- porate pollen grains occur, can be looked upon as a normal variation. The shape in equatorial view varies from prolate {P: E = 1.33-2) to suboblate [P : E = 0.88-0.75) and is mostly oval to rhomboidal. In some cases the shape is rectangular to compressed oval (Alchemilla type). The shape in polar view is mostly circular to semiangular, sometimes intersubangular (Alchemilla type) or subangular (Mespilus The sometimes broad type). colpi are usually narrow, (Sanguisorba officinalis subtype). In some types the colpi are accompanied by costae colpi (Alchemilla type, Rosa canina type, Rosa gallica type, Rubus idaeus type). Opercula can be present (Potentilla type, Sanguisorba type, Rosa canina type, Rosa gallica type). The polar area index (P.Ä.I.) from Ó.1 Costae sometimes ranges to 0.55. endocolpi or endopori are present (Rosa rubiginosa subtype, Geum subtype). The Rosaceae studied are all striate, both extra- and intrastriate. The last structure is mostly only visible with the phase-contrast microscope. The striae on the tectum are formed by some strong, more or less fused, capita. Columellae, however, do not occur in the striae. all have a tectum, which Mostly grains except Mespilus , has a tectum perforatum. On the structural elements of different be found tectum shape may such as scabrae (Filipendula type), echinae, verrucae or gemmae (Rubus chamaemorus type). All these grains have a fastigium, which is also found in other Fabaceae tricolporate grains e.g. Sedum, Solanum, p.p., Apiaceae p.p. 4.2. Description and discussion Crataegus type (Faegri and Iversen, 1964) Figs. 1, 2 Diagnosis: tricolporate; fastigiate; psilate; intrastriate, mostly only visible with C.I. phase contrast; > 4; subprolate-suboblate; eq. view: oval-rhomboidal; pol. view: circular-semiangular; max. 23-42 length: fi. Absent: operculum; costae colpi. Species studied Crataegus monogyna Jacq. 33912B, [U]; Gulperberg Crataegus oxyacantha L. 071886B, [U]; Utrecht Aronia melanocarpa (Michx.) Ell. Wassenaar Sorbus aria (L.) Crantz 115592B, [U] Sorbus aucuparia L. Utrecht 294 TJ. REITSMA 1. Fig. Crataegus monogyna Jacq. Fig. 2. Sorbus aucuparia L. 3 Mespilus type Fig. Diagnosis: tricolporate (tricolpate); fastigiate; striate; tectum per- C.I. oblate foratum; > 4; spheroidal-prolate spheroidal; eq. view: oval-rhomboidal; pol. view: circular-subangular. Absent: operculum; costae colpi. Species studied Mespilus germanica L. 011015 [U]; Onderste Bos (Epen) P.A.I.: 0.2-0.3: maximum 42-49 length: fi. Rubus idaeus 5 type Figs. 4, Diagnosis: tricolporate; fastigiate; psilate; intrastriate, mostly only visible with phase contrast; costae colpi; C.I.