Comparative pollen morphology and taxonomic ... - CNCFlora

92 R.L.B. de Borges et al. / Review of Palaeobotany and Palynology 154 (2009) 91–105
Table 1
Previous morphological pollen data of representatives of the Eriocaulaceae family
Authors Taxa Method Subject
Erdtman (1943) Eriocaulon septangulare Withering LM Pollen morphology and plant taxonomy - Angiosperms
Kuprianova (1948) Eriocaulon benthamii Kunth and Paepalanthus blepharocnemis Mart. LM Pollen morphology of monocotyledons
Erdtman (1952) Syngonanthus wahlbergii (Wikstr.) Ruhl and Tonina fluviatilis Aubl. LM Pollen morphology and plant taxonomy - Angiosperms
Ikuse (1956) Eriocaulon miquelianum Körn., E. nipponicum Maxim., E. parvum Körn,
E. senile Honda, and E. sielboldianum Sieb. et Zucc. (= E. cinereum R. Br.)
LM Pollen flora of Japan
Thanikaimoni (1965) Eriocaulon L. (46 spp.), Lachnocaulon Kunth (2 spp.),
Leiothrix Ruhland (1 sp.), Paepalanthus Mart. (1 sp.),
Philodice Mart. (1 sp.), Syngonanthus Ruhland (2 spp.),
and Tonina Aubl. (1 sp.)
LM Pollen morphology of the Eriocaulaceae family
Huang (1972) Eriocaulon cinerum R. Br. Var. sieboldianum (Sieb. & Zucc.) T. Kayama,
E. merrillii Ruhl., E. nantoense Hay., E. trisectum Satake,
E. truncatum Buch.-Ham.
LM Pollen flora of Taiwan
Ybert (1979) Mesanthemum prescottianum (Bong.) Körn. LM Pollen flora of the Ivory Coast
Furness (1988) Eriocaulon aquaticum (Hill) Druce. LM, SEM Eriocaulaceae in the Northwest European pollen flora
Santos et al. (2000) Actinocephalus (8 spp.) and Paepalanthus (7 spp.) LM Pollen morphology of some Brazilian Eriocaulaceae
Rull (2003) Paepalanthus perplexans Mold. LM Illustrated pollen key of some Venezuelan species
Coan et al. (2007a) Syngonanthus caulescens (Poir.) Ruhland SEM Embryological study of the species, only SEM pictures
of pollen grains were presented
Coan et al. (2007b) Leiothrix fluitans (Mart.) Ruhland SEM Embryological study of the species, only SEM pictures
of pollen grains were presented
Method: LM — light microscopy, SEM — scanning electron microscopy.
The first study of the Eriocaulaceae using scanning electron
microscopy was undertaken by Furness (1988), who described the
pollen grains of Eriocaulon aquaticum (Hill) Druce. Coan et al. (2007a,b)
published electro-micrographs of the pollen grains of Syngonanthus
caulescens (Poir.) Ruhland and Leiothrix fluitans (Mart.) Ruhland as a
part of their study of the embryology of these taxa.
Considering all the pollen morphological data related to the
Eriocaulaceae to date, only 87 taxa have been described, of which 60 are
species belonging to the genus Eriocaulon. Furthermore, the principal
pollen study of the family (Thanikaimoni, 1965) was published 43 years
ago and employed only light microscopy. For these reasons, the objective
of the present work was to provide a more complete study of the family
and to clarify the patterns of the pollen apertures exhibited by the different
taxonomic groups, using both light and scanning electron microscopy.
2. Materials and methods
In accordance with Ruhland's (1903) classification system for
Eriocaulaceae, we studied the pollen grains of 55 species from the
genera Actinocephalus, Blastocaulon, Eriocaulon, Lachnocaulon, Leiothrix,
Paepalanthus, Philodice, Rondonanthus, Syngonanthus, andTonina. The
genus Mesanthemum was not included in this work due to the lack of
study material, but both of the subfamilies cited by Ruhland (1903),
Eriocauloideae and Paepalanthoideae, were considered. Taxonomic
arrangement of the group is:
Order Poales
Fam. Eriocaulaceae
Subfam. Eriocauloideae
Eriocaulon 400/4 1
Mesanthemum 12/0
Paepalanthoideae
Actinocephalus 29/6
Blastocaulon 5/2
Lachnocaulon 7/2
Leiothrix 37/9
Paepalanthus 485/15
Philodice 2/1
Rondonanthus 6/1
Syngonanthus 200/14
Tonina 1/1
1 Total number of species/number of species included in present study.
Pollen samples (the capitula) for our analyses were obtained from
herbarium specimens that had been securely identified and incorporated
into the Herbário da Universidade Estadual de Feira de Santana —
HUEFS, Herbarium of the Miami University — MU, and Herbário do
Departamento de Botânica, Instituto de Biociências (Universidad de São
Paulo) — SPF. All of the specimens examined are listed in the Appendix A.
The acetolysis method (Erdtman, 1960) was used for the light
microscope (LM) analysis of the pollen grains of 36 species. For each
species, at least 20 pollen grains were used (except when not possible)
in the morphometric analyses of the principal pollen parameters:
diameter, width of the interapertural exine strip, thickness of the
exine layers, and length of the spines.
For the scanning electron microscopy (SEM) studies, 41 species of the
above-mentioned genera were examined. Due to the fragile nature of
the pollen grains and their low production, the anthers were removed
from the flowers and opened directly over a stub covered by doublefaced
self-adhesive carbon tape. The material was subsequently coated
with gold and analyzed (LEO 1430 VP — Carl Zeiss).
Photographs of the pollen characteristics were obtained under
both LM and SEM techniques. The palynological nomenclature used
follows Punt et al. (2007), and that of the type of aperture follows
Pozhidaev (2000).
All of the prepared material is deposited in the palynotheca of the
Laboratory of Plant Micromorphology (LAMIV) at the Universidade
Estadual de Feira de Santana, Bahia State, Brazil.
3. Results
3.1. General pollen morphology
All species of Eriocaulaceae studied here had pollen grains that
were monads, generally spherical, and varied in size from small (up to
25 µm) to medium (N25 µm) (Table 2). The smallest pollen grains are
observed in Blastocaulon albidum, Lachnocaulon minus, Paepalanthus
tortilis, and P. subtilis, while the largest grains are seen in Paepalanthus
comans, P. planifolius (both P. subg. Platycaulon) and Rondonanthus
duidae. Variations among the sizes of the pollen grains of the same
specimen are relatively large: up to 14 µm as recorded for Syngonanthus
schwackei (T. B. Cavalcanti et al. 2906) and 15 µm for Paepalanthus
pulvinatus (M. J. G. Andrade 106). This fact may be due to
rupturing of the aperture during chemical treatment (acetolysis),
which increases the size of the pollen grains.
Constant features among the pollen grains of the species of
Eriocaulaceae that were analyzed are the spiral apertures and that the