Pollen morphology of NW European representatives con¢rm monophyly of Rubieae (Rubiaceae) Suzy Huysmans a , Steven Dessein a , Erik Smets a; , Elmar Robbrecht b a Laboratory of Plant Systematics, Institute of Biology and Microbiology, K.U.Leuven, Kasteelpark Arenberg 31, 3001 Leuven, Belgium b NationalBotanic Garden, Domein van Bouchout, 1860 Meise, Belgium Received 6 December 2002; received in revised form 11 July 2003 ; accepted 11 August 2003 Abstract This study focuses on the six genera of Rubieae thatoccur in NW Europe: Asperula, Crucianella, Cruciata, Galium, Rubia, and Sherardia. The pollen morphology of 29 species was studied using light microscope and sca electron microscope observations. Several features demonstrate the advanced nature of the tribe : simple ape to 13 ectocolpi, supratectal microspines, a characteristic and unique endopattern, and absence of orbicules. As Cruciata, Galium,and Rubia cannot be distinguished by pollen morphology only. The monospecific genus Sherardia can be recognized easily by the high numbers of apertures (10^13) that are slit-like and the very fine perforat the tectum. Some Crucianella species have relatively larger perforations in the tectum. None of the species inv produces orbicules, which makes Rubieae, next to Gardenieae, the second rubiaceous tribe entirely without or Our palynological data are interpreted in the broader perspective of all herbaceous Rubiaceae. The Rubieae are unique among Rubiaceae in the combination of the following pollen features: several colpate apertures, a perforate and microechinate tectum, a relatively small size,the absence of endoapertures, a coarse nexine area beneath the ectocolpi, and the absence of orbicules. The predictive value of pollen morphology is therefore extremely high triballeveland supports the monophyly of Rubieae. 6 2003 Elsevier B.V. All rights reserved. Keywords: endopatterns ; orbicules ; pollen morphology; Rubiaceae; systematics 1. Introduction Rubiaceaeare a predominantly tropical and woody plant family. About 10 tribes ( Robbrecht, 1988) of the family, however, are (predominantly) herbaceous and approximately 18% of all rubia- ceousgenera are non-woody. One of the tribes with mostly herbaceous species are the Rubieae, which accommodates 13 genera with an estimated 670 species in total (Robbrecht, 1988, 1994). Their herbaceous growth habit and occurrence in tem- perate areas indicate the advanced nature of the taxa included. The tribe is characterized by ‘ver- ticillate’ leaves and raphides. The ‘leaf whorls’ are in fact whorls of true leafbladesand modi¢ed stipules(Rutishauser, 1984).The terminalin£o- rescences have £owerswith rudimentary calyces 0034-6667 / 03 / $ ^ see front matter 6 2003 Elsevier B.V. All rights reserved. doi :10.1016/S0034-6667(03)00121-0 * Corresponding author. Tel. :+32-16-32-15-35; Fax: +32-16-32-19-68. E-mailaddresses : erik.smets@bio.kuleuven.ac.be (E. Smets), e.robbrecht@br.fgov.be (E. Robbrecht). Review of Palaeobotany and Palynology 127 (2003) 219^240 R Available online at www.sciencedirect.com www.elsevier.com/locate/revpalbo