Register      Login
Australian Systematic Botany Australian Systematic Botany Society
Taxonomy, biogeography and evolution of plants
RESEARCH ARTICLE

Pollen of the Spermacoce (Rubiaceae) species from the Northern Territory of Australia: morphology and taxonomic significance

S. Dessein A D , R. Harwood B , E. Smets A and E. Robbrecht C
+ Author Affiliations
- Author Affiliations

A Laboratory of Plant Systematics, Institute of Botany and Microbiology, K.U.Leuven, Kasteelpark Arenberg 31, B-3001 Leuven, Belgium.

B Northern Territory Herbarium, PO Box 496, Palmerston, NT 0831, Australia.

C National Botanic Garden of Belgium, Domein van Bouchout, B-1860 Meise, Belgium.

D Corresponding author. Email: steven.dessein@bio.kuleuven.ac.be

Australian Systematic Botany 18(4) 367-382 https://doi.org/10.1071/SB03025
Submitted: 10 September 2003  Accepted: 6 April 2005   Published: 31 August 2005

Abstract

Complementary to the revision of the genus Spermacoce in the Northern Territory of Australia, pollen morphology of 48 of the 53 native Spermacoce species from the Northern Territory has been investigated by scanning electron and light microscopy. There is considerable variation for most diagnostic pollen characters. The average equatorial diameter (E) ranges from 10.5 to 41.7 µm. Grains are invariably colporate with the apertures situated at the equator (being zonocolporate). The number of apertures varies from 3 to 17. The endoaperture is generally an endocingulum, often with a secondary thinning at the ectocolpus; one species has endocolpi. The sexine is usually perforate, but psilate, foveolate, and (micro)reticulate patterns were also found. Supratectal elements are present as granules or microspines scattered over the whole surface or confined to a region around the ectoapertures. The inner nexine surface is granular, often with irregular grooves (endocracks).

The pollen morphological variation observed allows the distinction of four pollen types. Three of these types are not yet recorded in other palynological studies of Spermacoce. Pollen characters are often useful to delimit species and groups of related species.


Acknowledgments

We thank Marcel Verhaegen from the National Botanic Garden of Belgium for taking SEMs from the pollen grains, and Suzy Huysmans and an anonymous reviewer for the valuable comments on the first drafts of this manuscript. Steven Dessein is a postdoctoral fellow of the Fund for Scientific Research, Flanders (FWO-Vlaanderen). Financial support for this study was provided by project OT/01/25 from the Research Fund of the K.U.Leuven.


References


Bremekamp CEB (1952) The African species of Oldenlandia L. sensu Hiern et K. Schumann. Verhandelingen der Koninklijke Nederlandse Akademie van Wetenschappen, Afdeeling Natuurkunde, Tweede sectie 48, 1–297. open url image1

Bremekamp CEB (1966) Remarks on the position, the delimitation and the subdivision of the Rubiaceae. Acta Botanica Néerlandica 15, 1–33. open url image1

Dessein S (2003) ‘Systematic studies in the Spermacoceae (Rubiaceae).’ PhD thesis, Katholieke Universiteit Leuven, Belgium.

Dessein S, Huysmans S, Robbrecht E, Smets E (2002a) Pollen of African Spermacoce species (Rubiaceae): morphology and evolutionary aspects. Grana 41, 69–89.
Crossref | GoogleScholarGoogle Scholar | open url image1

Dessein S, Jansen S, Robbrecht E, Smets E (2002b) A new species of Spermacoce (Rubiaceae) from the Manika high plateau (Katanga; R.D.Congo). Nordic Journal of Botany 2, 513–523. open url image1

Dessein S, Ntore S, Robbrecht E, Smets E (2003) Pollen and seeds reveal that Spermacoce thymoidea s.l. (African Rubiaceae, Spermacoceae) represents three endemic or disjunct species from the Zambesian high plateaus. Systematic Botany 28, 130–144. open url image1

Ganders FR (1979) The biology of heterostyly. New Zealand Journal of Botany 17, 607–635. open url image1

Grayum MH (1986) Correlations between pollination biology and pollen morphology in the Araceae with some implications for angiosperm evolution. In ‘Pollen and spores: form and function. Linnean Society symposium series. Vol. 12’. (Eds S Blackmore, IK Ferguson) pp. 313–327. (Academic Press: London)

Harwood B, Dessein S (2005) Australian Spermacoce (Rubiaceae: Spermacoceae). I. Northern Territory. Australian Systematic Botany 18, 297–365. open url image1

Huysmans S, Robbrecht E, Smets E (1994) Are the genera Hallea and Mitragyna (Rubiaceae–Coptosapelteae) pollen morphologically distinct? Blumea 39, 321–340. open url image1

Huysmans S, Robbrecht E, Smets E (1998) A collapsed tribe revisited: pollen morphology of the Isertieae (Cinchonoideae–Rubiaceae). Review of Palaeobotany and Palynology 104, 85–113.
Crossref | GoogleScholarGoogle Scholar | open url image1

Huysmans S, Robbrecht E, Delprete P, Smets E (1999) Pollen morphological support for the Catesbaeeae–Chiococceae–Exostema-complex (Rubiaceae). Grana 38, 325–338.
Crossref | GoogleScholarGoogle Scholar | open url image1

Huysmans S, Dessein S, Smets E, Robbrecht E (2003) Pollen morphology of NW European representatives confirms monophyly of Rubieae (Rubiaceae). Review of Palaeobotany and Palynology 127, 219–240.
Crossref | GoogleScholarGoogle Scholar | open url image1

Johansson JT (1987) Pollen morphology of the tribe Morindeae (Rubiaceae). Grana 26, 134–150. open url image1

Keddam-Malplanche M (1985) Le pollen et les stomates de Gardéniées (Rubiacée) du Gabon. Morphologie et tendances évolutives. Mémoires du Muséum national d’Histoire naturelle. Série B, Botanique 29, 1–109. open url image1

Lewis WH (1965) Cytopalynological study of African Hedyotideae (Rubiaceae). Annals of the Missouri Botanical Gardens 52, 182–211. open url image1

Lobreau-Callen D , Leroy JF (1980) Quelques données palynologiques sur le genre Coffea et autres genres du cercle des cafiers. In ‘9e colloque, London’. pp. 479–506. (Association Scientifique Internationale du Café: London)

Muller J (1979) Form and function in angiosperm pollen. Annals of the Missouri Botanical Gardens 66, 593–632. open url image1

Piesschaert F, Huysmans S, Jaimes I, Robbrecht E, Smets E (2000) Morphological evidence for an extended tribe Coccocypseleae (Rubiaceae–Rubioideae). Plant Biology 2, 536–546.
Crossref | GoogleScholarGoogle Scholar | open url image1

Pire SM (1996) Palynological study of American species of Borreria (Rubiaceae–Spermacoceae). Opera Botanica Belgica 7, 416–423. open url image1

Punt W (1986) Functional factors influencing pollen form. In ‘Pollen and spores: form and function. Linnean Society symposium series. Vol. 12’. (Eds S Blackmore, IK Ferguson) pp. 97–101. (Academic Press: London)

Punt W , Blackmore WS , Nilsson S , Le Thomas A (1994) ‘Glossary of pollen and spore terminology.’ (LPP Foundation: Utrecht)

Reitsma T (1969) Size modifications of recent pollen grains under different treatments. Review of Palaeobotany and Palynology 9, 175–202.
Crossref | GoogleScholarGoogle Scholar | open url image1

Robbrecht E (1988) Tropical woody Rubiaceae. Characteristic features and progressions. Contributions to a new subfamilial classification. Opera Botanica Belgica 1, 1–272. open url image1

Schols P, Dessein S, D’hondt C, Huysmans S, Smets E (2002) Carnoy: a new digital measurement tool for palynology. Grana 41, 124–126.
Crossref | GoogleScholarGoogle Scholar | open url image1

Thanikaimoni G (1986) Pollen apertures: form and function. In ‘Pollen and spores: form and function. Linnean Society Symposium Series. Vol. 12’. (Eds S Blackmore, IK Ferguson) pp. 119–136. (Academic Press: London)

Verdcourt B (1958) Remarks on the classification of the Rubiaceae. Bulletin du Jardin Botanique de l’État. Bruxelles 28, 209–290. open url image1

Vermoesen C (1922) De fijnere structuur der stuifmeelkorrels en hunne systematische beteekenis bij de Angiospermen. Natuurwetenschappelijk Tijdschrift 4, 1–12. open url image1