Braz. J. Bot (2015) 38(4):937–950
DOI 10.1007/s40415-015-0192-4
Pollen morphology of some Brazilian Xyris Gronov. ex L.
(Xyridaceae) species
Cynthia Fernandes Pinto da Luz1 • Valéria Leobina dos Santos1 • Juliana Santos Guedes2
Gisele de Oliveira Silva-Cobra2 • Maria das Graças Lapa Wanderley2
•
Received: 29 March 2015 / Accepted: 3 July 2015 / Published online: 15 July 2015
Ó Botanical Society of Sao Paulo 2015
Abstract Although the pollen morphology of Xyridaceae
shows standard patterns that distinguish five genera,
specific data of each genus are scarce or incompletely
known. The pollen morphology of 17 Brazilian species of
Xyris (Nematopus Section) based upon 47 specimens from
Goiás and Minas Gerais States, Brazil, is presented.
Micrographs of pollen grain structures were obtained using
light and scanning electron microscopy. Pollen grains are
characterized as monads, medium to large sized, ellipsoidal
in polar view, flattened/convex in equatorial view and
monosulcates. The sulci are pontoperculate and covered
with an insulae type membrane. The sexine presents either
a microreticulum or rugulae with perforations, and is
thicker than the nexine. Although Xyris is a stenopalynous
genus, characterized by monosulcate pollen grains, two
groups of species were recognized based upon pollen size
as well as pollen wall ornamentation features. Therefore,
pollen data are of taxonomic value and useful to clarify the
delimitation of the studied species.
Keywords Monocots Palynotaxonomy Pollen
morphology Xyris
Electronic supplementary material The online version of this
article (doi:10.1007/s40415-015-0192-4) contains supplementary
material, which is available to authorized users.
& Cynthia Fernandes Pinto da Luz
cyluz@yahoo.com.br
1
Núcleo de Pesquisa em Palinologia, Instituto de Botânica,
Av. Miguel Stéfano, 3687, São Paulo, SP 04301-012, Brazil
2
Núcleo de Pesquisa Curadoria do Herbário, Instituto de
Botânica, São Paulo, Brazil
Introduction
Xyridaceae comprises five genera and ca. 427 species
occurring widely in tropical and subtropical regions
worldwide: Xyris Gronov. ex L. (ca. 400 sp.), Abolboda
Humb. & Bonpl. (ca. 23 sp.), Aratitiyopea Steyerm. & P.E.
Berry (1 sp.), Orectanthe Maguire (2 sp.) and Achlyphila
Maguire & Wurdack. (1 sp.) (Kral 1998; Wanderley 2003;
Campbell 2004; Wanderley and Silva 2009; Wanderley
2010). Nearly 90 % of the taxa occur in rocky fields along
the Espinhaço Mountain Range (Bahia and Minas Gerais
States, Brazil), which represents one of the centres of the
family diversity (Wanderley and Silva 2009; Silva 2010;
Wanderley 2010). The widespread genus Xyris in Brazil
includes approximately 170 species (Silva and Wanderley
2013).
Xyridaceae, also known as the yellow-eyed grass family
is very diverse in Brazil, highlighting Xyris as the largest
genus of the family, with a wide concentration of its representatives in the Espinhaço Range. In this region, it is
common to find several species co-occurring at the same
locality; however, the delimitation of such species is
unclear due to many overlapping reproductive and vegetative characters (Wanderley 2011). Pollen morphology
may be useful to contribute to the taxonomy of Xyris.
Palynological research on Xyridaceae is stucking by
limited suitable samples, due to the remote locations of
most populations and the brief floral phenology (Carlquist
1960; Campbell 2004, 2012). Erdtman (1952) briefly
studied the pollen morphology of Abolboda and Xyris,
showing that the pollen grains are similar to those occurring in certain genera of Liliaceae and Pontederiaceae.
Carlquist (1960) studied the family more extensively,
including several species of Abolboda, Orectanthe and
Achlyphila. Lisowski et al. (2001) studied 18 species of
123
938
C. F. P. Luz et al.
Xyris, none of which are included in this study. Few studies
only presented data from scanning electron microscopy
(Rudall and Sajo 1999; Campbell 2004, 2012; Campbell
and Stevenson 2007; Hesse et al. 2009).
Pollen morphology of some Brazilian species of Xyris
was presented by Cruz-Barros et al. (2000), Melhem et al.
(2003) and Salgado-Labouriau and Villar de Seoane
(1992). They were described as heteropolar, ellipsoidal in
polar view and flattened/convex in equatorial view. Pollen
grain descriptions vary in regard to one (1-colpus or
1-sulcus) or two (2-colpi or 2-sulci) long apertures. The
presence of three sulci was suggested by Erdtman (1952)
for the Brazilian species of X. rupicula Kunth. Apertures
were described as long, varying from narrow to wide, with
a more or less irregular outline, approximately so long as
the largest equatorial diameter, in which the apertural
membrane could show ornamentation (ORN) or not. A
pontoperculum has not always been indicated.
The sexine pattern has been described as difficult to
distinguish, characterized either as reticulate, foveolate,
punctate, scabrous or simply as finely ornamented
(Kuprianova 1948; van Zinderen Bakker 1953; Sharma
1967; Huang 1970, 1972; Ybert 1979; Kral 1983; Zavada
1983; Straka and Friedrich 1984; Salgado-Labouriau and
Villar de Seoane 1992; Rudall and Sajo 1999; Cruz-Barros
et al. 2000; Melhem et al. 2003; Campbell 2004). Pollen
grains of Xyris were characterized as stenopalynous, i.e.
with a high degree of homogeneity. Its pollen characteristics were considered inferior for taxonomic diagnosis on
species level (Carlquist 1960; Campbell 2012).
According to Campbell (2012), palynological research
of Xyridaceae in the future may include the characterization of great lineages of Xyris species to test the hypothesis
that pollen grains are always elliptic.
In order to better understand the relationship among
Brazilian species of Xyris, pollen morphology in the
delimitation of species and/or groups of species of the
Nematopus Section was investigated.
Paulo (Brazil) and in the herbarium of the Universidade
Federal dos Vales do Jequitinhonha e Mucuri (DIAM),
Minas Gerais, Brazil. Pollen grains were acetolysed following Erdtman (1960). Measurement averages comprised
25 pollen grains per sample. Measurements of morphological structures were based upon ten pollen grains per
sample. Dimensions of other morphological structures
were obtained of ten pollen grains per sample. More than
one specimen per taxon were investigated to identify any
possible intra-specific variation. The specimen marked
with an asterisk (*) within the list of species (Tables 1 and
2) represents the material used for illustration of pollen
grains.
To verify whether the pollen grain characteristics
allowed the grouping of species, a principal component
analysis (PCA) was performed using the programmes
FITOPAC (Shepherd 1996) and PC-ORD versão 7
(McCune & Mefford 1999). For this analysis, we used one
qualitative parameter ORN and seven metric variables:
larger diameter (DIAM 1) and shorter diameter (DIAM 2)
in equatorial view, exine thickness (EXI), nexine thickness
(NEX), sexine thickness (SEX), length of sulcus (LSUL)
and width of sulcus (WSUL) (Table 3).
Photomicrographs (LM) were obtained using an
OLYMPUS BX 50 light microscope with a video camera
and the CellSens software for Windows. Scanning electron
microscope images of the acetolysed pollen grains were
obtained using a PHILIPS XL 20 microscope of the
Instituto de Botânica of the São Paulo State (Brazil) and
JSM-5800 LV-JEOL microscope of the Universidade de
Campinas, São Paulo, Brazil. The acetolysed pollen grains
were dehydrated using ethanol, spread directly on the
microscope stubs and sputtered with a 20-nm-thick gold
layer. Terminology follows Punt et al. (2007) and Hesse
et al. (2009). The microscope slides were deposited in the
palynotheca of the Núcleo de Pesquisa em Palinologia of
the Instituto de Botânica.
Materials and methods
Results and discussion
Pollen morphology of 17 Brazilian species represented by
47 specimens of Xyris was surveyed (Tables 1 and 2).
Pollen data for the genus is summarized in Table 4 were
obtained from Kuprianova (1948), Erdtman (1952), van
Zinderen Bakker (1953), Sharma (1967), Huang (1970),
(1972), Ybert (1979), Straka and Friedrich (1984), Rudall
and Sajo (1999), Cruz-Barros et al. (2000), Melhem et al.
(2003), Campbell (2004) and in the present study also.
Samples were removed from flower buds obtained in the
Herbario Cientı́fico do Estado ‘‘Maria Eneyda P. Kauffmann Fidalgo’’ (SP) of the Instituto de Botânica of São
Even though the Brazilian species of Xyris are stenopalynous, pollen grain size and ORN features are the most
variable structures and can be used for pollen grain characterization (Figs. 1–69).
Pollen grains are medium to large sized, the longest axis
reaching 69.9 lm, ellipsoidal in polar view, flattened/convex in equatorial view and monosulcate (Table 1). The sulci
are pontoperculate and covered with an insulae type
membrane (the sulcus is covered by exine granules or
scattered exine elements). The sexine is tectate, thicker than
the nexine (Table 2). The pontoperculum which covers part
123
Species
Larger equatorial diameter (EM)
Shorter equatorial diameter (Em)
X
Sx
S
CI
X
Sx
S
Xyris asperula Mart. (SP 430224)*
45.9
0.8
3.8
8.4
44.3–47.5
30.2
0.4
2.1
7.0
29.3–31.1
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. asperula Mart. (SP 210413)
53.9
0.5
3.8
7.1
52.9–55.0
31.3
0.3
2.6
8.5
30.6–32.0
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. asperula Mart. (SP 210447)
53.8
0.6
5.3
9.8
52.4–55.3
34.1
0.2
1.2
3.6
33.8–34.5
Ellipsoidal (polar view), flattened/convex (equatorial view)
Xyris aurea L.B. Sm. & Downs (SP 430239)*
49.3
0.7
3.5
7.0
47.9–50.7
29.5
0.4
2.1
7.1
28.6–30.4
Ellipsoidal (polar view), flattened/convex (equatorial view)
V%
V%
Form
CI
X. aurea L.B. Sm. & Downs (SP 346197)
59.0
0.4
3.4
5.7
58.1–59.9
37.2
0.5
4.0
10.9
36.1–38.3
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. aurea L.B. Sm. & Downs (SP294737)
57.7
0.4
3.6
6.3
56.7–58.7
33.7
0.3
2.4
7.2
33.1–34.4
Ellipsoidal (polar view), flattened/convex (equatorial view)
Xyris bialata Malme (SP 382088)*
50.2
0.8
3.9
7.8
48.6–51.9
30.0
0.6
2.9
9.8
28.8–31.2
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. bialata Malme (SP423607)
45.8
0.3
2.7
6.0
45.1–46.6
27.7
0.3
2.5
9.2
27.0–28.3
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. bialata Malme (SP412365)
49.6
0.5
3.8
7.6
48.6–50.6
29.8
0.3
2.8
9.3
29.0–30.5
Ellipsoidal (polar view), flattened/convex (equatorial view)
Xyris calostachys Poulsen (SP203772)*
50.3
0.9
4.4
8.8
48.5–52.1
31.4
1.0
4.8
15.2
29.4–33.4
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. calostachys Poulsen (SP 204858)
52.3
0.6
5.0
9.6
51.0–53.7
34.0
0.5
4.3
12.7
32.9–35.2
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. calostachys Poulsen (SP 298458)
52.0
0.6
5.0
9.5
50.7–53.4
30.3
0.3
2.4
7.9
29.7–31.0
Ellipsoidal (polar view), flattened/convex (equatorial view)
Xyris cipoensis L.B. Sm & Downs (SP221689)*
63.8
0.6
3.2
5.0
62.5–65.1
37.8
0.4
1.9
5.1
37.0–38.6
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. cipoensis L.B. Sm & Downs (SP 234960)
59.6
0.6
5.2
8.8
58.2–61.1
34.4
0.4
3.3
9.7
33.4–35.3
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. cipoensis L.B. Sm & Downs (SP 204739)
56.6
0.7
5.7
10.1
55.0–58.1
32.2
0.4
2.9
8.9
31.4–33.0
Ellipsoidal (polar view), flattened/convex (equatorial view)
Xyris diamantinae Malme (DIAM 79-3)*
67.8
1.0
5.0
7.4
65.7–69.9
37.7
0.6
2.9
7.7
36.5–38.9
Ellipsoidal (polar view), flattened/convex (equatorial view)
Xyris filifolia Alb. Nilsson (DIAM 62-3)*
51.3
1.0
5.0
9.8
49.2–53.4
32.5
0.5
2.4
7.3
31.5–33.5
Ellipsoidal (polar view), flattened/convex (equatorial view)
Xyris fredericoi Wand (SP2211745)*
57.2
0.8
3.9
6.8
55.6–58.8
34.1
0.6
3.1
9.0
32.8–35.4
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. fredericoi Wand (CFSC11631)
62.8
0.5
3.7
5.9
61.8–63.8
35.6
0.4
3.1
8.6
34.8–36.4
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. fredericoi Wand (SP221186)
58.9
0.6
5.0
8.5
57.5–60.3
35.7
0.4
3.1
8.6
34.9–36.6
Ellipsoidal (polar view), flattened/convex (equatorial view)
Xyris hystrix Seub (SP 204593)*
52.7
0.7
3.7
7.1
51.2–54.2
34.8
0.5
2.3
6.5
33.9–35.8
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. hystrix Seub (Col. Wanderley 2932)
52.7
0.4
3.2
6.0
51.8–53.6
31.2
0.2
1.9
6.1
30.6–31.7
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. hystrix Seub (SP 83406)
51.4
0.4
3.5
6.8
50.4–52.3
37.3
0.2
2.0
5.3
36.7–37.8
Ellipsoidal (polar view), flattened/convex (equatorial view)
Xyris insignis L.A.Nilsson (SP430207)*
48.9
0.7
3.7
7.6
47.4–50.4
29.9
0.4
2.1
7.1
29.0–30.8
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. insignis L.A.Nilsson (Col. Wanderley 2950)
58.0
0.5
4.1
7.1
56.8–59.1
33.4
0.6
4.8
14.5
32.0–34.7
Ellipsoidal (polar view), flattened/convex (equatorial view)
48.6
0.7
5.4
11.2
47.1–50.1
34.4
0.4
3.1
8.9
33.5–35.2
Ellipsoidal (polar view), flattened/convex (equatorial view)
Xyris longiscapa L.A.Nilsson (Col. Silva et al. 20)*
65.7
1.1
5.4
8.3
63.5–68.0
36.5
0.8
4.0
11.0
34.8–38.1
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. longiscapa L.A.Nilsson (SP384310)
63.2
0.5
4.4
7.0
62.0–64.5
36.8
0.3
2.7
7.2
36.0–37.5
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. longiscapa L.A.Nilsson (SP 258345)
68.3
0.5
4.3
6.3
67.1–69.4
36.6
0.3
2.2
6.1
36.0–37.2
Ellipsoidal (polar view), flattened/convex (equatorial view)
Xyris melanopoda L.B.Sm. & Downs (SP 183419)*
44.4
0.7
3.3
7.4
43.0–45.7
27.0
0.5
2.5
9.2
25.9–28.0
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. melanopoda L.B.Sm. & Downs (SP 170002)
45.4
0.4
2.9
6.4
44.6–46.2
25.1
0.4
3.2
12.7
24.2–26.0
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. melanopoda L.B.Sm. & Downs (SP 116998)
44.9
0.4
3.4
7.5
44.0–45.8
24.6
0.2
1.7
6.9
24.2–25.1
Ellipsoidal (polar view), flattened/convex (equatorial view)
Xyris obtusiuscula L.A.Nilsson (SP221734)*
60.9
1.4
6.9
11.4
58.0–63.7
37.3
0.6
3.1
8.3
36.0–38.6
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. obtusiuscula L.A.Nilsson (SP221168)
62.8
0.8
6.5
10.4
61.0–64.6
40.7
0.4
3.3
8.1
39.8–41.6
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. obtusiuscula L.A.Nilsson (SP221676)
62.8
0.6
4.8
7.7
61.5–64.1
38.5
0.5
3.9
10.2
37.5–39.6
Ellipsoidal (polar view), flattened/convex (equatorial view)
939
123
X. insignis L.A.Nilsson (SP 263502)
Pollen morphology of some Brazilian Xyris Gronov. ex L. (Xyridaceae) species
Table 1 Measures (lm) in equatorial view of Xyris pollen grains through light microscopy (n = 25)
47.4
X. trachyphylla Mart. (SP184571)
x arithmetic mean, sx average standard deviation, s sample standard deviation, V % coefficient of variability, CI confidence interval 95 %
Ellipsoidal (polar view), flattened/convex (equatorial view)
27.9–29.7
11.7
3.4
0.4
28.8
46.4–48.4
7.7
3.7
61.5
0.4
Ellipsoidal (polar view), flattened/convex (equatorial view)
Ellipsoidal (polar view), flattened/convex (equatorial view)
36.9–38.3
7.1
2.7
0.3
37.6
59.9–63.0
9.1
5.6
Ellipsoidal (polar view), flattened/convex (equatorial view)
X. trachyphylla Mart. (SP183415)
0.7
35.6–37.7
6.9
2.5
0.5
36.7
66.0–69.8
6.8
4.6
67.9
Xyris trachyphylla Mart. (Col. Silva et al. 35)*
0.9
Ellipsoidal (polar view), flattened/convex (equatorial view)
30.8–32.5
29.6–30.4
4.9
10.3
3.3
1.5
0.2
0.4
31.6
30.0
44.6–46.6
47.3–50.0
10.5
8.4
3.8
5.1
45.6
X. subsetigera Malme (SP202925)
0.5
48.7
X. subsetigera Malme (SP221147)
0.6
Ellipsoidal (polar view), flattened/convex (equatorial view)
Ellipsoidal (polar view), flattened/convex (equatorial view)
32.3–35.0
10.0
3.4
0.7
33.6
48.3–51.3
7.4
3.7
49.8
Xyris subsetigera Malme (SP221178)*
0.7
Ellipsoidal (polar view), flattened/convex (equatorial view)
30.9–32.5
26.8–27.6
5.8
9.3
3.0
1.6
0.2
0.4
31.7
27.2
45.0–46.8
45.7–47.4
6.7
7.4
3.4
3.1
45.9
X. seubertii L.A.Nilsson (SP203799)
0.4
46.6
X. seubertii L.A.Nilsson (SP333467)
0.4
Ellipsoidal (polar view), flattened/convex (equatorial view)
Ellipsoidal (polar view), flattened/convex (equatorial view)
27.3–29.4
9.1
2.6
0.5
28.4
43.8–46.1
6.3
2.8
44.9
Xyris seubertii L.A.Nilsson (Col. Kral et al. 72654)*
0.6
31.7–33.3
9.4
3.0
0.4
32.5
51.5–52.8
4.4
2.3
52.1
X. platystachya L.A. Nilsson ex Malme (SP221179)
0.3
36.3–39.0
30.9–34.2
12.4
13.0
4.9
4.0
0.8
0.6
37.7
32.5
51.3–53.3
54.5–57.7
10.4
4.7
2.4
5.8
0.7
56.1
X. platystachya L.A. Nilsson ex Malme (SP245330)
0.5
52.3
Xyris platystachya L.A. Nilsson ex Malme (SP178471)*
Sx
S
V%
CI
Sx
S
V%
CI
X
X
Form
Shorter equatorial diameter (Em)
Larger equatorial diameter (EM)
Species
Table 1 continued
123
Ellipsoidal (polar view), flattened/convex (equatorial view)
C. F. P. Luz et al.
Ellipsoidal (polar view), flattened/convex (equatorial view)
940
of the sulcus has the same morphological features as the
non-apertural sexine.
Two main pollen types could be recognized based upon
pollen grain size and the exine ORN using scanning electron microscopy data also. Two groups were formed by the
PCA, confirming the observations (Fig. 1).
The pollen variability among the species of Xyris
comprised 77.16 % on the two first axis in the PCA
(Fig. 1). The first axis summed 51.05 % of variance
according to the type of ORN and the highly correlated
values especially the width of the sulcus (WSUL) of the
pollen grains (Table 3).
On the left side of the graph were ordered the
microreticulate species associated with high values of the
metrics variables of its pollen grains, especially sexine
thickness (SEX) and exine thickness (EXI), shorter diameter
(DIAM2) and larger diameter in equatorial view (DIAM1).
In contrast, the rugulated-perforated species were ordered
on the right side of the graph associated with lower values
for the variables. The three species grouped above (X. aurea,
X. melanopoda and X. seubertii) showed the smaller diameter values among the rugulate-perforate pollen type.
Pollen type 1 comprises medium-sized pollen grains
with a rugulate-perforate surface (Xyris melanopoda
L.B.Sm. & Downs, Xyris seubertii L.A.Nilsson, Xyris
subsetigera Malme).
Pollen type 2 comprises large-sized pollen grains. Two
subtypes are recognized: the microreticulate pollen type
(Xyris calostachys Poulsen., Xyris diamantinae Malme,
Xyris longiscapa L.A.Nilsson, Xyris obtusiuscula
L.A.Nilsson) and the rugulate-perforate pollen type (Xyris
cipoensis L.B., Xyris filifolia Alb. Nilsson, Xyris fredericoi
Wand, Xyris hystrix Seub, Xyris platystachya L.A. Nilsson
ex Malme).
These two pollen types are taxonomically related, corroborate by pollen morphology. The latter is composed by
everlasting plants.
However, Xyris species of X. asperula Mart., X. aurea
L.B. Sm. & Downs, X. bialata Malme, X. insignis L.A.
Nilsson and X. trachyphylla Mart showed a great intraspecific variation, being difficult to characterize them by
pollen size. The exine ORN allows a separation into two
groups: the microreticulate pollen type (X. asperula Mart.,
X. bialata Malme, X. insignis L.A.Nilsson, X. trachyphylla
Mart) and the rugulate-perforate pollen type (X. aurea L.B.
Sm. & Down). The variation of pollen grain morphology of
these species reflects a similar overlapping already registered for other taxonomical characteristics, such as the
shape of the ear, the bract and the vegetative character
(Wanderley 2011).
Heteropolarity, elliptic or ellipsoidal form, a long sulcus
and the sexine being wider than the nexine, are palynological
characteristics of Xyris in conformity with the actual
Pollen morphology of some Brazilian Xyris Gronov. ex L. (Xyridaceae) species
941
Table 2 Arithmetic average of measures (lm) of the sulcus and thickness of the exine layers of the Xyris pollen grains through light microscopy
(n = 10)
Species
Sulcus
WM
Exine
LS
WS
Tectum
Sexine
Nexine
Xyris asperula Mart. (SP 430224)*
4.63
35.70
20.75
0.31
0.61
0.50
X. asperula Mart. (SP 210413)
4.35
47.60
16.20
–
–
–
X. asperula Mart. (SP 210447)
Xyris aurea L.B. Sm. & Downs (SP 430239)*
5.16
4.57
45.50
38.63
25.61
18.78
–
0.32
–
0.58
–
0.50
X. aurea L.B. Sm. & Downs (SP 346197)
6.26
50.55
15.75
–
–
–
X. aurea L.B. Sm. & Downs (SP 294737)
6.24
49.56
21.49
–
–
–
Xyris bialata Malme (SP 382088)*
4.30
43.72
22.19
0.65
0.71
0.60
X. bialata Malme (SP 423607)
4.85
37.87
14.77
–
–
–
X. bialata Malme (SP 412365)
4.77
41.26
20.38
–
–
–
Xyris calostachys Poulsen (SP 203772)*
4.85
43.73
20.78
0.46
0.60
0.50
X. calostachys Poulsen (SP 204858)
4.90
46.17
21.21
–
–
–
X. calostachys Poulsen (SP 298458)
4.49
46.41
20.74
–
–
–
Xyris cipoensis L.B. Sm & Downs (SP 221689)*
7.16
47.30
18.10
0.61
0.85
0.68
X. cipoensis L.B. Sm & Downs (SP 234960)
6.83
49.76
24.62
–
–
–
X. cipoensis L.B. Sm & Downs (SP 204739)
4.00
52.85
20.18
–
–
–
Xyris diamantinae Malme (DIAM 79-3)*
5.10
44.87
15.12
0.25
0.96
0.72
Xyris filifolia Alb. Nilsson (DIAM 62-3)*
6.60
42.82
15.24
0.28
0.78
0.49
Xyris fredericoi Wand (SP 2211745)*
X. fredericoi Wand (CFSC 11631)
3.67
3.98
44.73
54.46
17.12
24.33
0.54
–
0.69
–
0.58
–
X. fredericoi Wand (SP 221186)
3.89
47.40
23.12
–
–
–
Xyris hystrix Seub (SP 204593)*
9.95
42.05
18.92
0.54
0.67
0.54
X. hystrix Seub (Col Wanderley 2932)
6.07
41.85
22.56
–
–
–
X. hystrix Seub (SP 83406)
7.47
44.94
23.20
–
–
–
Xyris insignis L.A. Nilsson (SP 430207)*
6.48
42.12
19.78
0.47
0.64
0.52
X. insignis L.A.Nilsson (Col. Wanderley 2950)
6.35
52.45
21.80
–
–
–
X. insignis L.A.Nilsson (SP 263502)
4.79
44.50
22.56
–
–
–
Xyris longiscapa L.A.Nilsson (Col. Silva et al. 20)*
3.17
56.92
18.91
0.44
0.62
0.52
X. longiscapa L.A.Nilsson (SP 384310)
3.65
58.15
28.14
–
–
–
X. longiscapa L.A.Nilsson (SP 258345)
6.55
60.38
21.86
–
–
–
Xyris melanopoda L.B. Sm. & Downs (SP 183419)*
4.26
38.43
21.57
0.46
0.55
0.50
X. melanopoda L.B.Sm. & Downs (SP 170002)
4.49
38.41
20.92
–
–
–
X. melanopoda L.B.Sm. & Downs (SP 116998)
4.71
39.09
19.63
–
–
–
Xyris obtusiuscula L.A. Nilsson (SP 221734)*
7.97
49.30
26.67
0.38
0.67
0.61
X. obtusiuscula L.A. Nilsson (SP 221168)
X. obtusiuscula L.A. Nilsson (SP 221676)
6.69
5.01
55.19
55.96
27.72
21.54
–
–
–
–
–
–
Xyris platystachya L.A. Nilsson ex Malme (SP 178471)*
3.63
40.80
14.67
0.53
0.77
0.54
X. platystachya L.A. Nilsson ex Malme (SP 245330)
4.62
45.36
28.51
–
–
–
–
X. platystachya L.A. Nilsson ex Malme (SP 221179)
4.41
45.26
20.21
–
–
Xyris seubertii L.A. Nilsson (Col. Kral et al. 72654)*
7.72
35.79
17.86
0.48
0.69
0.60
X. seubertii L.A.Nilsson (SP 333467)
3.72
36.13
20.51
–
–
–
–
X. seubertii L.A.Nilsson (SP 203799)
4.14
42.11
21.22
–
–
Xyris subsetigera Malme (SP 221178)*
6.07
41.18
12.16
0.48
0.70
0.54
X. subsetigera Malme (SP 221147)
6.68
38.43
21.40
–
–
–
–
X. subsetigera Malme (SP 202925)
4.95
39.20
17.08
–
–
Xyris trachyphylla Mart. (Col. Silva et al. 35)*
8.06
56.81
29.35
0.49
0.70
0.60
X. trachyphylla Mart. (SP 183415)
4.76
44.82
20.54
–
–
–
123
942
C. F. P. Luz et al.
Table 2 continued
Species
Sulcus
X. trachyphylla Mart. (SP 184571)
Exine
WM
LS
WS
Tectum
Sexine
Nexine
4.66
41.79
24.98
–
–
–
WM widht of one side of the sulcus membrane, LS length of the sulcus, WS width of the sulcus
Table 3 Pearson and Kendall coefficients for pollen grain metric
variables of the first two axis of PCA ordination of Xyris Gronov. ex L
knowledge. However, it differs as to the size of the pollen
grains, number of apertures, the presence or not of a pontoperculum, and type of the exine ORN (Kuprianova 1948;
Erdtman 1952; van Zinderen Bakker 1953; Sharma 1967;
Huang 1970, 1972; Ybert 1979; Straka and Friedrich 1984;
Rudall and Sajo 1999; Cruz-Barros et al. 2000; Melhem et al.
2003; Campbell 2004) (Table 4).
The pollen grain size of Xyris species formerly studied
can be smaller or bigger than the size of the present species.
Large pollen grain variation at the intra-specific level was
detected among some specimens studied, showing that size
is not a stable characteristic for species differentiation.
Pollen grains of Xyris cipoensis, X. diamantinae, X. fredericoi, X. longiscapa and X. obtusiuscula are the largest
ones, being distinguished from the remaining species.
The two specimens of Xyris trachyphylla are large sized.
The largest equatorial diameters vary, respectively,
between 53.4 and 74.9 lm and 41.6–51.8 lm, showing
marked dimensional amplitude.
Pollen grains sized below 50 lm, presenting a rugulateperforate ORN and the same morphological characteristics
of all specimens analysed of Xyris melanopoda, X. seubertii and X. subsetigera, distinguish them from the
remaining ones.
Fig. 1 Biplot of PCA for Xyris Gronov. ex L. species, of the pollen
grain metric variables. (Xasp Xyris asperula, Xaur X. aurea, Xbia X.
bialata, Xcal X. calostachys, Xcip X. cipoensis, Xdia Xyris diamantinae, Xfil Xyris filifoli, Xfre X. fredericoi, Xhys X. hystrix, Xins X.
insignis, Xlon X. longiscapa, Xmel X. melanopoda, Xobt X.
obtusiuscula, Xpla X. platystachya, Xseu X. seubertii, Xsub X.
subsetigera, Xtra X. trachyphylla). Ornamentation (ORN), Larger
diameter (DIAM1) and shorter diameter (DIAM2) in equatorial view,
exine thickness (EXI), nexine thickness (NEX), sexine thickness
(SEX), length of sulcus (LSUL) and width of sulcus (WSUL)
Variables
Principal components
Axis 1
Axis 2
DIAM1
-0.3005
-0.5523
DIAM2
-0.1622
-0.4389
SEX
0.0098
-0.2264
NEX
EXI
-0.0417
-0.0172
-0.1218
-0.2287
LSUL
-0.3390
-0.3723
WSUL
-0.5825
0.4734
0.6535
-0.1444
ORN
123
Pollen morphology of some Brazilian Xyris Gronov. ex L. (Xyridaceae) species
Figs. 2–16 Light micrographs of Xyris pollen grains. 2–4 Xyris
asperula Mart. 2 Optical section, polar view. 3 Surface and sulcus,
equatorial view. 4 Optical section, equatorial view. 5–7 Xyris aurea
L.B.S. & Downs. 5 Optical section, polar view. 6 Surface and sulcus,
equatorial view. 7 Optical section, equatorial view. 8–10 Xyris bialata
Malme. 8 Optical section, polar view. 9 Surface and sulcus, equatorial
943
view. 10 Optical section, equatorial view. 11–13 Xyris calostachys
Poulsen. 11 Optical section, polar view. 12 Surface and sulcus,
equatorial view. 13 Optical section, equatorial view. 14–16 Xyris
cipoensis L.B.Sm. & Downs. 14 Optical section, polar view. 15
Surface and sulcus, equatorial view. 16 Optical section, equatorial
view. Bar 10 lm
123
944
C. F. P. Luz et al.
Figs. 17–24 Light micrographs of Xyris pollen grains. 17, 18 Xyris
diamantinae Malme. 17 Surface and sulcus, polar view. 18 Surface
and sulcus, equatorial view. 19, 20 Xyris filifolia Alb. Nilsson. 19
Optical section, polar view. 20 Surface and sulcus, equatorial view.
21–23 Xyris fredericoi Wand. 21 Optical section, polar view. 22
Optical section, equatorial view. 23, 24 Xyris hystrix Seub. 23 Optical
section, polar view. 24 Optical section, equatorial view. Bar 10 lm
The sulci of Xyris pollen grains are pontoperculate and
covered with an insulae type membrane. The pontoperculum was defined by Erdtman (1952) as being an operculum,
not completely isolated from the rest of the ectexine and
showing the shape of a long ‘‘bridge’’ (Thanikaimoni 1983;
Punt et al. 2007). Therefore, the pollen grains of some
Xyris species were defined as 1-sulcate (Erdtman 1952; van
Zinderen Bakker 1953; Sharma 1967; Melhem et al. 2003),
while other species as 2-sulcate (Erdtman 1952; Straka and
Friedrich 1984; Cruz-Barros et al. 2000). Erdtman (1952)
further mentioned the possibility that X. rupicola Kunth
from Brazil may have 3 sulci, but made it clear that he was
not sure.
Among the species studied here, only Xyris longiscapa,
X. obtusiuscula and X. trachyphylla were formerly analysed (Rudall and Sajo 1999). Our results corroborate with
these results, as this pollen grains were classified as
monosulcate and operculate. However, only one scanning
123
Pollen morphology of some Brazilian Xyris Gronov. ex L. (Xyridaceae) species
945
Figs. 25–36 Light micrographs of Xyris pollen grains. 25–27 Xyris
insignis L.A. Nilsson. 25 Surface and sulcus, polar view. 26 Surface
and sulcus, equatorial view. 27 Optical section, equatorial view. 28–
30 Xyris longiscapa L.A. Nilsson. 28 Surface and sulcus, polar view.
29 Surface and sulcus, equatorial view. 30 Optical section, equatorial
view. 31–33 Xyris melanopoda L.B.Sm. & Downs. 31 Optical
section, polar view. 32 Surface and sulcus, equatorial view. 33
Optical section, equatorial view. 34–36 Xyris obtusiuscula L.A.
Nilsson. 34 Optical section, polar view. 35 Surface and sulcus,
equatorial view. 36 Optical section, equatorial view. Bar 10 lm
electron micrograph of the equatorial view of a X. obtusiuscula pollen grain was presented, and none in light
microscopy. It seems that what was called as an operculum
is really a pontoperculum of Erdtman (1952). Also, the
ORN is microreticulate and not reticulate as described,
corroborating our results.
The description of the exine ORN of Xyris pollen
grains varies according to the authors (Table 4). However,
none of them, except Rudall and Sajo (1999) and
Campbell (2004), used scanning electron microscopy.
Smooth variations can only be shown using high magnification. It was possible to establish by this technique two
groups of species, the first presenting a microreticulate
exine ORN (X. asperula, X. bialata, X. calostachys, X.
diamantinae, X. insignis, X. longiscapa, X. obtusiuscula,
X. trachyphylla), and the second a rugulate-perforate
structure (X. aurea, X. cipoensis, X. filifolia, X. fredericoi,
X. hystrix, X. melanopoda, X. platystachya, X. seubertii,
X. subsetigera). A sexine thicker than the nexine was
always observed.
123
946
C. F. P. Luz et al.
Figs. 37–45 Light micrographs of Xyris pollen grains. 37, 38 Xyris
platystachya L.A. Nilsson ex Malme. 37 Optical section, polar view.
38 Surface and sulcus, equatorial view. 39, 40 Xyris seubertii L.A.
Nilsson. 39 Optical section, polar view. 40 Surface and sulcus,
equatorial view. 41–43 Xyris subsetigera Malme. 41 Surface and
sulcus, polar view. 42 Surface and sulcus, equatorial view. 43 Optical
section, equatorial view. 44, 45 Xyris trachyphylla Mart. 44 Surface
and sulcus, polar view. 45 Surface and sulcus, equatorial view.
Bar 10 lm
In Furness and Rudall (1999), pollen grains from Xyris
trachyphylla in various stages of maturity were submitted
to examination in differential interference contrast microscope and it was ascertained that the type of the
microsporogenesis is successive and related to the pattern
of tetrahedral tetrad and apertures of monosulcate type that
shown in this species. We assumed that all the species
analysed here are monosulcate and pontoperculate.
123
Pollen morphology of some Brazilian Xyris Gronov. ex L. (Xyridaceae) species
947
Figs. 46–57 Scanning electron micrographs of Xyris pollen grains,
details of exine surface. 46, 47 Xyris asperula Mart. 48 Xyris aurea
L.B.Sm. & Downs. 49 Xyris bialata Malme. 50 Xyris calostachys
Poulsen. 51 Xyris cipoensis L.B.Sm. & Downs. 52 Xyris diamantinae
Malme. 53, 54 Xyris filifolia Alb. Nilsson. 55 Xyris fredericoi Wand.
56, 57 Xyris hystrix Seub. Bar 10 lm (46, 53, 56); 1 lm (47–49, 51,
55); 2 lm (50, 52, 54, 57)
The contribution of pollen morphology to the taxonomy
of Xyris offers few parameters, pointing to assemblages of
palynological-related species only. Although the genus is
considered stenopalynous, the pollen grain characteristics
of some Brazilian species analysed suggest that they are of
taxonomic value. Transmission electron microscopy may
provide important data for the taxonomy of Xyris, especially in terms of a better understanding of the apertures.
123
948
Figs. 58–69 Scanning electron micrographs of Xyris pollen grains,
details of exine surface. 58 Xyris insignis L.A.Nilsson. 59 Xyris
longiscapa L.A.Nilsson. 60 Xyris melanopoda L.B.Sm. & Downs. 61,
62 Xyris obtusiuscula L.A.Nilsson. 63, 64 Xyris platystachya
123
C. F. P. Luz et al.
L.A.Nilsson ex Malme. 65 Xyris seubertii L.A.Nilsson. 66, 67 Xyris
subsetigera Malme. 68, 69 Xyris trachyphylla Mart. 68 Three pollen
grains. 69 Surface. Bar 2 lm (58, 69); 1 lm (59, 60, 64–66); 2 lm
(61–63, 66); 20 lm (68)
Pontoperculate
Operculate
Pseudooperculate (sin.
pontoperculate)
Presence or not
of operculum
Operculate or
pontoperculate
Not
mentioned
Pseudooperculate (sin.
pontoperculate)
Not
mentioned
Not
mentioned
Not
mentioned
Not
mentioned
Operculate
Not
mentioned
Not
mentioned
Microreticulate
or rugulate
with perforations
Finely
ornamented
Not clearly
visible
Sexine
ornamentation
Finely reticulate
or not clearly
visible
Finely
reticulate
Foveolate or
reticulate to
punctate
Granulate
Granulate
Reticulate
Foveolate
Reticulate
Microreticulate
Microreticulate
Sulcus
1
Sulcus
1
Colpus
1
Sulcus
2
1
Sulcus
Sulcus
1 or 2
1
Colpus
Sulcus
1
1
Sulcus
Colpus
1
1
Sulcus
Sulcus
Number of
aperture
1 or 2. 3(?)
Sulcus
1
Aperture type
17 of Brazil
(47
specimens)
1
2
Total of species
studied
4, Including 1 of
Brasil
1
2
1
1
1
2
3 of Brazil
(all
studied
here)
5 of Brazil
1 of Brazil
This study
Campbell
(2004)
Melhem
et al.
(2003)
CruzBarros
et al.
(2000)
Rudall
and
Sajo
(1999)
Straka
and
Friedrich
(1984)
Ybert
(1979)
Huang
(1972)
Huang
(1970)
Sharma
(1967)
van
Zinderen
Bakker
(1953)
Erdtman
(1952)
Kuprianova
(1948)
Table 4 Summary of aperture features and descriptions of ornamentation of sexine of pollen grains of Xyris according to some authors, compared to the results obtained in this research (last
column)
Pollen morphology of some Brazilian Xyris Gronov. ex L. (Xyridaceae) species
949
Acknowledgments We are grateful to the curators of the herbaria
who provided exsiccates (see specimens investigated). Financial
support was obtained from the Coordenação de Aperfeiçoamento de
Pessoal de Nı́vel Superior (CAPES). We also extend our thanks to the
Conselho Nacional de Desenvolvimento Cientı́fico e Tecnológico
(CNPq) for the fellowship of ‘‘Productivity in research’’ to the first
and fifth authors and for the scholarship (PIBIC) to the second author.
We are grateful to Luciana Benatti of the Instituto de Botânica for the
scanning electron micrographs.
References
Campbell LM (2004) Anatomy and systematics of Xyridaceae, with
special reference to Aratitiyopea Steyerm. & P.E. Berry.
Doctoral thesis, City University of New York, New York
Campbell LM (2012) Pollen morphology of Xyridaceae systematic
(Poales) and its potential. Bot Rev 78:428–439
Campbell LM, Stevenson DW (2007) Inflorescence architecture and
floral morphology of Aratitiyopea lopezii (Xyridaceae). Aliso
23:227–233
Carlquist S (1960) Anatomy of Guayana Xyridaceae: Abolboda,
Orectanthe, and Achlyphila. Mem N Y Bot Gard 10:65–117
Cruz-Barros MAV, Corrêa MAS, Silva EL (2000) Flora Polı́nica da
reserva do parque estadual das fontes do ipiranga (São Paulo,
Brasil). Hoehnea 27:215–218
Erdtman G (1952) Pollen morphology and plant taxonomy–angiosperms (An introduction to palynology I). Almqvist and
Wiksell, Stockholm
Erdtman G (1960) The acetolysis method. A revised description.
Sven Bot Tidskr 54:561–564
Furness CA, Rudall PJ (1999) Microsporogenesis in monocotyledons.
Ann Bot 84:475–499
Hesse M, Halbritter H, Zetter R, Weber M, Buchner R, FroschRadivo A, Ulrich S (2009) Pollen terminology: an illustrated
handbook. Springer, New York
Huang TC (1970) Pollen grains of formosan plants. Taiwania
15:73–179
Huang TC (1972) Pollen flora of Taiwan. National Taiwan University. Botany Department Press, Taiwan
Kral R (1983) The Xyridaceae in the Southeastern United States.
J Arnold Arbor 64:421–429
Kral R (1998) Supplemental notes on new world Xyris (Xyridaceae).
Novon 8:388–398
Kuprianova LA (1948) Morphologie des pollens et phylogénie des
Monocotylédones. Commun Komarov Inst Acad Sci 1:163–262
Lisowski S, Brylska B, Wiland-Szymańska J (2001) Xyridaceae.
Flore D’Afrique Centrale (Congo-Kinshasa-Rwanda-Burundi):
Spermatophytes. Jardin Botanique National de Belgique,
Brussels
Mccune B, Mefford MJ (1999) PC-ORD version 4.0, multivariate
analysis of ecological data, Users guide. Glaneden Beach,
Oregon: MjM Software Design
Melhem TS, Cruz-Barros MAV, Corrêa AMS, Makino-Watanabe H,
Silvestre-Capelato MEF, Esteves VLG (2003) Variabilidade
polı́nica em plantas de Campos do Jordão (São Paulo, Brasil).
Boletim do Instituto de Botânica 16, São Paulo
Punt W, Hoen PP, Blackmore S, Nilsson S, Le Thomas A (2007)
Glossary of pollen and spore terminology. Rev Paleobot Palynol
143:1–81
Rudall PJ, Sajo MG (1999) Systematic position of Xyris: flower and
seed anatomy. Int J Plant Sci 160:795–808
Salgado-Labouriau ML, Villar De Seoane L (1992) Contribución a la
flora polinica de los tepuyes. In: Huber O (ed) El macizo de
123
950
chimantá, escudo de guayana, venezuela: un ensayo ecologico
tepuyano. Oscar Todtmann Editores, Caracas, pp 219–236
Sharma M (1967) Pollen morphology of Indian monocotyledons.
J Palynol 167 (special number):98
Shepherd GJ (1996) Fitopac 1: manual do usuário. Departamento de
Botânica, Universidade Estadual de Campinas, Campinas
Silva GO (2010) Flora de mucugê, bahia, Brasil: Xyridaceae.
Dissertation, Instituto de Botânica de São Paulo
Silva GO, Wanderley MGL (2013) A famı́lia Xyridaceae no
municı́pio de Mucugê, BA, Brasil. Hoehnea 40:51–76
Straka H, Friedrich B (1984) Palynologia madagassica et mascarenica.
Fam. 19-49. Tropische Subtrop Pflanzenwelt 49:404–485
Thanikaimoni G (1983) Pollen apertures: form and function. In:
Blackmore S, Ferguson IK (eds) Pollen and spores: form and
function. The Linnean Society of London, London, pp 119–136
Van Zinderen-Bakker EM (1953) South African pollen grains and
spores. Part III. A.A. Balkema, Cape Town, pp 1–200
123
C. F. P. Luz et al.
Wanderley MGL (2003) Xyridaceae. In: Wanderley MGL, Shepherd
GJ, Giulietti AM, Melhem TS (eds) Flora fanerogâmica do
estado de São Paulo, vol 3. FAPESP, São Paulo, pp 333–348
Wanderley MGL (2010) Cinco novas espécies de Xyris (Xyridaceae)
da serra do cipó, Minas Gerais, Brasil. Rodriguésia 61:83–94
Wanderley MGL (2011) Flora da serra do cipó, minas Gerais:
Xyridaceae. Bol Bot Univ São Paulo 29:69–134
Wanderley MGL, Silva MBC (2009) Flora de grão mogol, minas
Gerais: Xyridaceae. Boletim de botânica da Universidade de São
Paulo 27:137–147
Ybert JP (1979) Atlas de pollens de Côte d’Ivoire. Initiations
Documentations Techniques 40. ORSTOM
Zavada MS (1983) Comparative morphology of monocot pollen and
evolutionary trends of apertures and wall structures. Bot Rev
49:331–379
Cynthia Fernandes Pinto da Luz