全 文 ：Journal of Systematics and Evolution 46 (1): 73–79 (2008) doi: 10.3724/SP.J.1002.2008.06120
(formerly Acta Phytotaxonomica Sinica) http://www.plantsystematics.com
Reappraisal of the generic status of Pteroxygonum (Polygonaceae) on the
basis of morphology, anatomy and nrDNA ITS sequence analysis
Wei SUN Zhong-Ze ZHOU * Ming-Zhen LIU He-Wen WAN Xiang DONG
(School of Life Sciences, Anhui University; Anhui Key Laboratory of Ecological Engineering and Biotechnology, Hefei 230039, China)
Abstract Gross morphology, fruit anatomy, tepal venation, pollen morphology, chromosome number and ITS
sequence of Pteroxygonum Damm. & Diels as well as other related genera (Polygonum, Fallopia, Reynoutria,
Fagopyrum, and Antenoron) have been investigated to evaluate the generic status of Pteroxygonum. Pt. giraldii
Damm. & Diels has three sharp horns at the base of fruit, which is distinctive among all the genera investigated.
Upon observation of fruits under a light microscope (LM), the exocarp of Pt. giraldii is usually thickened and
delimited by the rectangular cells with some sporadic undulating lumen, while that of Fagopyrum is thin-walled
and isodiametric to rectangular in the cell shape. Analysis of tepal venation was performed under a stereomicro-
scope, and two types of tepal venation were found in Fagopyrum and Pteroxygonum. The type I is trifid, observed
in Pt. giraldii, F. esculentum Moench, F. dibotrys (D. Don) Hara and F. tataricum (L.) Gaertn. The type II, found
in F. caudatum (Sam.) A. J. Li, F. urophyllum (Bur. & Franch.) H. Gross and F. gracilipes (Hemsl.) Damm. ex
Diels, has the main vein extending from tepal base with some secondary veins. Evidence from tepal venation
supports the previous classification in which Fagopyrum can be divided into a large-achene group and a
small-achene group. Pollen morphology was investigated under a scanning electron microscope (SEM). The exine
ornamentation of Pt. giraldii was finely reticulate with lumina diameter wider than muri width. The exine orna-
mentation in all the examined Fagopyrum species is, however, prominently sunken punctuate. The phylogenetic
analysis of nuclear ribosomal DNA (nrDNA) ITS sequences in Pteroxygonum and related genera indicated that all
the species form a well-supported monophyletic group with two clades. One includes Polygonum sect. Avicularia
Meisn., genus Fallopia and genus Reynoutria, and the other consists of other sections of Polygonum, genus
Fagopyrum and Pteroxygonum. The latter clade can be divided into two subclades. Fagopyrum species compose
the first one, while Pteroxygonum giraldii, species of Polygonum (except sect. Avicularia) and Antenoron form the
second one. In consideration of the above evidence, we conclude that Pteroxygonum is an independent genus in
tribe Persicarieae, and should not be merged into the genus Fagopyrum.
Key words fruit anatomy, tepal venation, pollen morphology, ITS, Pteroxygonum, Polygonaceae.
Pteroxygonum giraldii Damm. & Diels is a dis-
tinctive species in China (Dammer & Diels, 1905;
Gross, 1913; Jaretzky, 1925; Hedberg, 1946). Dam-
mer & Diels (1905) described the new genus Pter-
oxygonum with one species Pt. giraldii on the basis of
the distinct fruit (a winged achene with three sharp
horns at the base and an elongated floral tube in the
fruiting stage). Gross (1913), Jaretzky (1925), and
Hedberg (1946) subsequently accepted it as a genus.
However, Hedberg (1946) stated that Pteroxygonum is
similar to Fagopyrum Mill. and Oxygonum Burch. ex
Campderá and Antigonon Endl. in pollen morphology.
Most later researchers regarded Pteroxygonum as a
member of Fagopyrum, instead of an independent
genus (Haraldson, 1978; Ronse De Craene &
Akeroyd, 1988; Hong et al., 1998). Haraldson (1978)
placed F. giraldii (equivalent to Pt. giraldii) in the
monotypic Fagopyrum sect. Pteroxygonum (Damm. &
Diels) Harald. on the basis of sharp horns on the edges
of the fruit and well-developed secondary xylem,
which are also present in other Fagopyrum species,
such as F. suffruticosum F. Schmidt. Ronse De
Craene and Akeroyd (1988) suggested that morpho-
logical characteristics of Pt. giraldii, which has the
flattened filaments with a flap-like appendage on the
flowers, indicate its close affinity with Fagopyrum,
instead of being an independent taxon.
Polygonaceae is included in the broadly defined
Caryophyllales as a sister group of Plumbaginaceae
(Savolainen et al., 2000; Soltis et al., 2000) and the
positions of Muehlenbeckia Meisn. and Fagopyrum
are not very clear (Cuénoud et al., 2002). Phylogenetic
relationship within Polygonaceae has been investi-
gated using the chloroplast gene rbcL. The result
suggested that Polygonum s.l. is paraphyletic (Lamb
Frye & Kron, 2003). Phylogenetic relationships
among Fagopyrum species have been investigated

———————————
Received: 4 August 2006 Accepted: 25 December 2006
* Author for correspondence. E-mail: .
Journal of Systematics and Evolution Vol. 46 No. 1 2008 74
using RFLP of chloroplast DNA (Ohnishi & Matsu-
oka, 1996), and the sequences of rbcL-accD region of
cpDNA (Yasui & Ohnishi, 1998a) and ITS regions of
the nrDNA (Yasui & Ohnishi, 1998b). These studies
suggested that Fagopyrum comprises two major
groups, namely, the cymosum group and the urophyl-
lum group.
The purpose of this study is to clarify the contro-
versial position of Pt. giraldii.
1 Material and methods
1.1 Molecular analysis of ITS sequences
Total cellular DNA was extracted from silica-gel
dried leaf materials or herbarium specimens (Table 1),
following the CTAB procedure with modifications
(Doyle and Doyle, 1987). The two internal transcribed
spacers (ITS-1, ITS-2) and 5.8S rDNA were amplified
using the primers named P18S (5′-CGTAACAAGGT-
TTCCGTAGGTGAAG-3′) and P26S (5′-TTATT-
GATATGCTTAAACTCAGCGGG-3′). 1.5 µL tem-
plate DNA, 1 µL 10 pmol of each primer, 0.5 µL Taq
DNA polymerase, 3 µL 10×puffer, 1.8 µL MgCl2, 2
µL dNTPs (5 U/µL), and 19.2 µL H2O were added
into 30 µL PCR reaction mixture. PCR reactions were
carried out by the following procedure: initial denatu-
ration 95 °C for 4 min, 33 cycles of 95 °C for 1 min,
52°C for 1 min, and 72 °C for 1 min, and then final
extension at 72 °C for 10 min. PCR products were
purified on 1% agarose gels using the QIAquick®
purification kit and directly sequenced on an ABI
3770 automated sequencer (Invitrogen Biotechnology
Co., Ltd). Sequencing primers were the same with
those of the previous PCR and used singly in forward
and reverse reactions. The maximum parsimony (MP)
analyses were undertaken using PAUP* 4.0 (Swof-
ford, 1998) using the heuristic search with 1000
replicates, random sequence addition, tree-bisection-
reconnection (TBR) branch swapping, Multrees in
effective. The gaps were treated as missing values.
1.2 Tepal venation, fruit anatomy and pollen
morphology observation
Dried floral parts were softened by boiling, and
then tepal venation observation was made under a
stereomicroscope. Fresh fruits were fixed in FAA,
sectioned on a sliding microtome and stained by
safranin. Fruits from the herbarium specimens were
boiled shortly before fixation. Pollen for light mi-
croscopy (Leitz Diaplan microscope) was prepared by
the standard acetolysis method outlined by Erdtman
(1960). Materials were subsequently mounted in
glycerine jelly. Pollen and tepals were ion-coated with
gold-palladium and photographed with a JSM-6300
scanning electron microscope. Measurements were
made under oil immersion and based on 20 pollen
grains per species.


Table 1 Source of materials for molecular experiments and morphological investigation
Species Voucher

Locality GenBank number/
morphology
Polygonum aviculare L. M. Z. Liu 05410 (ANU) Dali, Yunnan DQ406624
P. viviparum L. W. Sun 05442 (ANU) Lijiang, Yunnan DQ372903
P. campanulatum Hook. f. W. Sun 05430 (ANU) Dêqên, Yunnan DQ406630
P. perfoliatum L. Z. Z. Zhou 05414 (ANU) Hefei, Anhui DQ372904
P. hydropiper L. H. W. Wan 05710 (ANU) Hefei, Anhui DQ346665
Pteroxygonum giraldii Damm. & Diels Z. Z. Zhou 05744 (ANU) Song Shan, Henan DQ406627/pollen morphol-
ogy
Rumex acetosella L. AF189730*
Fallopia multiflora (Thunb.) Harald. AF040053*
Reynoutria japonica Houtt. AF040071*
Fagopyrum capillatum Ohnishi AB000323*
F. homotropicum Ohnishi AB000333*
F. esculentum Moench Z. Z. Zhou 2049 (ANU) Wenchuan, Sichuan tepal venation
F. dibotrys (D. Don) Hara Z. Z. Zhou 201103 (ANU) Zhenjiang, Zhejiang tepal venation
F. tataricum (L.) Gaertn. Z. Z. Zhou 2036 (ANU) Jiuzhaigou, Sichuan tepal venation
F. caudatum (Sam.) A. J. Li Z. Z. Zhou 2046 (ANU) Mao Xian, Sichuan tepal venation
F. urophyllum (Bur. & Franch.) H. Gross Z. Z. Zhou 2043 (ANU) Jiuzhaigou, Sichuan tepal venation
F. gracilipes (Hemsl.) Damm. ex Diels Z. Z. Zhou 8001 (ANU) Xiangyun, Yunnan AB000332*/ Tepal venation
F. lineare (Sam.) Harald. Z. C. Zhao 0170 (CDBI) Binchuan,Yunnan pollen morphology
Antenoron filiforme (Thunb.) Rob. & Vaut. (Tovara
filiformis (Thunb.) Nakai)
U51274*
* Sequences from GenBank.
SUN et al.: Reappraisal of the generic status of Pteroxygonum

75
2 Results
2.1 Morphological properties of Pteroxygonum
giraldii
Pteroxygonum giraldii is a perennial climbing
herb, with terete, striate and glabrous stems, up to 3 m
long. The inflorescence in Pt. giraldii is racemose.
Achenes are dark brown, ovoid, ca. 1 cm long and
well exceeding the persistent perianth, trigonous,
winged along angles, and 3-horned at base (Li et al.,
2003).
The cross-section of pericarp in Pt. giraldii has
three layers. The outer layer is usually thickened and
delimited by the rectangular cells with some sporadic
undulating lumen (Fig. 1).
In this study, the tepal vasculature from Pt. gi-
raldii and six species in Fagopyrum were investi-
gated. Based on tepal venation, two types could be
defined. The type I is trifid, which was found in Pt.
giraldii, F. esculentum, F. dibotrys, and F. tataricum.
The type II, occurring in F. caudatum, F. urophyllum,
and F. gracilipes, has the main vein extending from
tepal base with some secondary veins (Figs. 3, 4).
We merely observed the adaxial tepal surface of
Pt. giraldii under SEM. The epidermal cells are
mostly irregularly rectangular, with the anticlinal
walls being undulating (Fig. 5).
2.2 Pollen morphology of Pt. giraldii and F. linear
(Figs. 6–8)
2.2.1 Pt. giraldii (Figs. 6, 7) Pollen grains are
3-colporate; 62.9–69.7×49.3–62.9 µm, subprolate to
prolate (P/E=1.22–1.41). Oblong in equatorial view
and circular in polar view. Ectoaperture is colpus,
rather long; endoaperture is porus, with circular
outline, 8.5 µm in diameter, margin indistinct. Exine is
5.1 µm thick, with finely reticulate ornamentation.
Lumina diameter is wider than muri width.
2.2.2 Fagopyrum Pollen grains are 3-colporate;
25.5–49.3×23.1–37.4 µm, subprolate to prolate
(P/E=1.07–1.50), oblong in equatorial view and
circular in polar view. Ectoaperture is colpus, rather
long; endoaperture is porus, with circular outline,
3.0–6.0 µm in diameter. Exine is 2.5–5.0 µm thick,
with prominently sunken punctuate ornamentation
under SEM. This pollen type was found in all species
of Fagopyrum, illustrated here by F. lineare, Fig. 8
(Zhou et al., 2003, Figs. 1–27).
2.3 Results of the ITS analysis (Fig. 9)
The length of the aligned ITS sequence including
5.8S rDNA is 537–658 bp and 231 equally most
parsimonious trees were generated. Their strict con-
sensus tree is shown in Fig. 8 with 338 steps, a con-
sistent index (CI) of 0.7041, and a retention index (RI)
of 0.6644. Polygonum sect. Avicularia Meisn.,




















Figs. 1–8. 1. Pteroxygonum giraldii, showing thickened pericarp and undulated lumen. Scale bar=10 µm. 2. Fagopyrum esculentum (see Ronse De
Craene et al., 2000, Fig. 33), showing scattered bundles in mesocarp, crushed endocarp and absence of inner space between opposite wall-layers.
Scale bar=10 µm. 3. Tepal morphology of F. caudatum, F. urophyllum and F. gracilipes, showing a main vein from base with some secondary veins.
4. Tepal morphology of Pt. giraldii, F. esculentum, F. dibotrys and F. tataricum showing trifid tepal venation. 5. SEM Tepal morphology of Pt.
giraldii. 6. SEM micrographs of pollen in Pt. giraldii, showing uniform lumen. 7. LM micrographs of pollen in Pt. giraldii. Scale bar=10 µm. 8. SEM
micrographs of pollen in F. lineare, showing prominently sunken punctuate. Scale bar=10 µm.

Journal of Systematics and Evolution Vol. 46 No. 1 2008 76
















Fig. 9. The strict consensus tree generated from nrDNA ITS sequences using Rumex acetosella as an outgroup.


Fallopia Adans. and Reynoutria Houtt. form clade A;
clade B consists of Pteroxygonum, Antenoron, Poly-
gonum (sect. Bistorta (Adans.) D. Don, sect. Persi-
caria (Mill.) Meisn., sect. Aconogonon Meisn., sect.
Echinocaulon Meisn.) and Fagopyrum. The ITS data
indicate that clade B is divided into two subclades:
clade C and clade D. Clade C contains Pt. giraldii, P.
hydropiper, A. filiforme, P. perfoliatum, P. viviparum,
and P. campanulatum, while clade D includes F.
homotropicum, F. capillatum, and F. gracilipes.
Furthermore, Pt. giraldii is moderately supported as
the sister of the remaining species in Clade C (boot-
strap values = 60%).
3 Discussion
3.1 Achene morphology (Fig. 10)
Achene morphology of Pt. giraldii might be of
systematic significance for distinguishing the species
from other genera. It has three sharp horns at the base
of fruits, which were observable in F. suffruticosum
(P. suffruticosum) according to Haraldson (1978).
Haraldson took the special horns of Pt. giraldii as the
evidence of its relationship with Fagopyrum. A dif-
ferent understanding based on Steward (1930) was
realized on the description of F. suffruticosum. The
different origin between the sharp horns at the base
and dentations in the wings were not recognized by
Haraldson (1978). Therefore, the generic status of
Pteroxygonum is supported by the sharp horns in our
opinion.
3.2 Chromosome number
The basic chromosome number of Pt. giraldii is
20 (Haraldson, 1978). Fagopyrum has been suffi-
ciently studied in this respect (Chen, 1999), and the
basic chromosome number in the genus is evidently 8.
The basic numbers of related genera and sections are
as follows: Fallopia x=10, 11; Muehlenbeckia x=10;
Rheum L. x=11; Rumex L. x=7, 9, 10; Polygonum sect.
Aconogonon x=10, 11; Polygonum sect. Bistorta
x=11; Polygonum sect. Persicaria x=10, 11, 12(Hong,
1989). Hence, the chromosomal number data seem to
be inconsistent with the idea that Pteroxygonum and
Fagopyrum are closely related.
3.3 Tepal venation and SEM morphology
The tepals of Pt. giraldii have 3 veins arising
from the base. The tepal venation of the other genera
in the tribe Persicarieae is basically similar to that of
Pt. giraldii (Ronse De Craene & Akeroyd, 1988).
Therefore we deem that Pt. giraldii belongs to the

Fig. 10. SEM micrograph of achene in Pteroxygonum giraldii,
showing the difference origin between the wing and the horn.
SUN et al.: Reappraisal of the generic status of Pteroxygonum

77
tribe Persicarieae. Our result shows two distinctively
different types of tepal venation in Fagopyrum. In
type I, tepal venation is trifid. In type II, the tepals
have a main vein from base with some secondary
veins. Our result disagrees to Ronse De Craene and
Akeroyd’s (1988) comment that there is only trifid
type of tepal venation in Fagopyrum. Therefore, we
incline not to use tepal venation as a taxonomic index
to define systematic position of Fagopyrum in the
tribes Persicarieae or Polygoneae. Interestingly, the
two types of venation in Fagopyrum correspond to
two sections of Fagopyrum defined as the
large-achene group and the small-achene group (Oh-
nishi & Matsuoka, 1996; Yasui & Ohnishi, 1998a, b;
Chen, 1999). Further investigation needs to be per-
formed for all Fagopyrum species.
Hong et al. (1998) described three patterns of
sculpturing and cell shape in Persicarieae and Poly-
goneae. In type I, the epidermal cells are mostly
rectangular to narrowly rectangular, with the anticlinal
walls being straight or slightly undulating, and the
cuticular layer being longitudinally and undulately
striate. In type II, the epidermal cells are elongated
and irregular in shape, and strongly ridged, with the
anticlinal walls being deeply or shallowly undulating,
and the cuticular layer being irregularly and undu-
lately striate. In type III, the epidermal cells are
irregular in shape, and papillose, with the anticlinal
walls being straight and prominent, and the cuticular
layer being densely and longitudinally striate.
Hong et al. (1998) hesitated to ascertain a defi-
nite position of Fagopyrum, and agreed to Ronse De
Craene’s viewpoint that Fagopyrum should be placed
at the base in the Persicarieae. We reinvestigated
adaxial tepal surface of Pt. giraldii under SEM and
saw little change from the previous description (Hong
et al., 1998). The outline of the inner tepal epidermal
cells of Pt. giraldii is irregularly rectangular, and
anticlinal walls of the cells are undulating, with the
cuticles being irregularly striate. Based on the defini-
tion of cell shape and sculpturing in Persicarieae and
Polygoneae (Hong et al., 1998), the cell shape of
Persicarieae is mostly rectangular to elongate with
straight or undulating anticlinal walls, the cuticles
being smooth or striate in longitudinal direction and
often continuous. The cell shape of Polygoneae is
irregularly tessellated to elongated, rarely rectangular
with mostly sinuate anticlinal walls, the cuticles rarely
with longitudinal striation, but with strong orthogonal
to reticulate ridges or striae, often without correlation
between cells. Therefore, Pt. giraldii can be included
in the range of Persicarieae.
3.4 Fruit anatomy
Most of outer layer of the pericarp in Polygoneae
and Persicarieae is usually thickened and its anatomy
can be used to delimit genera more preferably than
any other features of the fruit (Ronse De Craene et al.,
2000). The outer layer of the pericarp in Pt. giraldii is
usually thickened and be delimited by the rectangular
cells with some sporadic undulating lumen. With
regard to exocarp, Pt. giraldii shows conspicuous
differences from Fagopyrum, whose exocarp is
thin-walled and isodiametric to rectangular in shape.
The mesocarp consists of several cell layers and
occupies most region of pericarp (Ronse De Craene et
al., 2000) (Fig. 2). Therefore, the independent generic
status of Pteroxygonum is supported, rather than as a
member of Fagopyrum.
The tribe circumscription in Polygonaceae and
Persicarieae is not applicable on basis of fruit anatomy
(Ronse De Craene et al., 2000), so we could not draw
a conclusion whether Pt. giraldii belongs to Persi-
carieae or not simply according to fruit anatomy.
3.5 Pollen morphology
Fagopyrum has 3-colporate pollen with a finely
reticulate ornamentation (Hedberg, 1946; Hong et al.,
1998). According to Hedberg (1946), the pollen of
Fagopyrum resembles that of Pteroxygonum, Oxy-
gonum and Antigonon, and thus a close relationship
between them was concluded. Hong (1988) amalga-
mated Harpagocarpus Hutch. & Dandy, Eskemuker-
jea Malick & Sengupta and Pteroxygonum into
Fagopyrum based on similar pollen morphology.
However, a distinct difference between Pteroxygonum
and Fagopyrum was found in our SEM study of
pollen. The pollen ornamentation of Pt. giraldii was
finely reticulate with lumina diameter wider than muri
width (Fig. 6), while the pollen ornamentation in all
the Fagopyrum species, illustrated here by F. linear,
Fig. 8 (Zhou et al., 2003, Figs. 1–27), is prominently
sunken punctuate. From the perspective of pollen
morphology, Pteroxygonum ought to be maintained as
an independent genus.
3.6 ITS analysis
Our ITS phylogeny contradicts some previous
viewpoints that Pt. giraldii has closer affinity with
Fagopyrum and should be classified into Fagopyrum
(Haraldson, 1978; Ronse De Craene & Akeroyd,
1988). The whole group under study is divided into
clade A and clade B, corresponding to tribes Poly-
goneae and Persicarieae, respectively. We found Pt.
giraldii and other groups form subclade C (60%
bootstrap support), and Fagopyrum forms subclade D
(100% bootstrap support). Together they form clade
Journal of Systematics and Evolution Vol. 46 No. 1 2008 78
B. Pt. giraldii was found in a well supported and
separate position in clade B. This result is consistent
with all the evidence presented above and supports the
treatment to elevate this species into a distinct genus.
Acknowledgements We are deeply grateful to Mr.
Jian-Yuan ZHAO, Mr. Ren-Xin XU, Ms. Li DUO and
Ms. Ling-Ling ZHANG for technical help with mo-
lecular experiment and microtome operation. We
sincerely thank Dr. Bao-Wei ZHANG (Institute of
Zoology) and Dr. Wan-Jin LIAO (Beijing Normal
University) for computer analysis. This work was
supported by the National Natural Science Foundation
of China, Grant No. 30670151, and the Natural Sci-
ence Foundation of Anhui, Grant Nos. 99042411,
03043102.
References
Chen Q-F. 1999. A study of resources of Fagopyrum
(Polygonaceae) native to China. Botanical Journal of the
Linnean Society 130: 53–64.
Cuénoud P, Saboleinen V, Chatrou LW, Powell M, Grayer RJ,
Chase MW. 2002. Molecular phylogenetic of
Caryophyllales based on nuclear 18S rDNA and plastid
rbcL, atpB, and matK DNA sequences. American Journal
of Botany 89: 132–144.
Dammer U, Diels L. 1905. Beiträge zur Flora des Tsin ling shan
und andere Zusätze zur Flora von Central-China.
Systematik, Pflanzengeschichte und Pflanzengeographie
36, Beibl 82: 36.
Doyle JJ, Doyle JL. 1987. A rapid DNA isolation procedure for
small quantities of fresh leaf tissue. Phytochemical
Bulletin 19: 11–15.
Erdtman G. 1960. The acetolysis method, a revised description.
Svensk Botanisk Tidskrift 54: 561–564.
Gross H. 1913. Remarques sur les Polygonées de l’Asie
Orientale. Bulletin de Géographie Botanique 23: 7–32.
Haraldson K. 1978. Anatomy and Taxonomy in Polygonoideae
Meisn. emend. Jaretzky. Acta Universitatis Upsaliensis.
Symbolae Botanicae Upsalienses. XXII: 2.
Hedberg O. 1946. Pollen morphology in the genus Polygonum
L. s.lat. and its taxonomical significance. Svensk Botanisk
Tidskrift 40: 371–404.
Hong SP. 1988. A pollen morphological re-evaluation of
Harpagocarpus and Eskemukerjea (Polygonaceae). Grana
27: 291–295.
Hong SP. 1989. Knorringia (Aconogonon sect. Knorringia), a
new genus in the Polygonaceae. Nordic Journal of Botany
9: 343–357.
Hong SP, Ronse De Craene LP, Smets E. 1998. Systematic
significance of tepal surface morphology in tribes
Persicarieae and Polygoneae (Polygonaceae). Botanical
Journal of Linnean Society 127: 91–116.
Lamb Frye AS, Kron KA. 2003. rbcL phylogeny and character
evolution in Polygonaceae. Systematic Botany 28:
326–332.
Li A-J (李安仁), Bao B-J (包伯坚) , Grabovskaya-Borodina
AE, Hong S-P, McNeill J, Mosyakin SL, Ohba H, Park
C-W. 2003. Polygonaceae. In: Wu Z-Y, Raven PH eds.
Flora of China. Beijing: Science Press; St. Louis: Missouri
Botanical Garden Press. 5: 277–350.
Jaretzky R. 1925. Beiträge zur Systematik der Polygonaceae
unter Berücksichtigung des Oxymethyl- anthrachinon-
Vorkommens: Feddes Repertorium Specierum Novarum
Regni Vegetabilis 22: 49–83.
Ohnishi O, Matsuoka Y. 1996. Search for the wild ancestor of
buckwheat. II. Taxonomy of Fagopyrum (Polygonaceae)
species based on morphology, isozymes and cpDNA
variability. Genes and Genetic Systems 71: 383–390.
Ronse De Craene LP, Akeroyd JR. 1988. Generic limits in
Polygonum and related genera (Polygonaceae) on the basis
of floral characters. Botanical Journal of Linnean Society
98: 321–371.
Ronse De Craene LP, Hong SP, Smets E. 2000. Systematic
significance of fruit morphology and anatomy in tribes
Persicarieae and Polygoneae (Polygonaceae). Botanical
Journal of Linnean Society 134: 301–377.
Savolainen V, Chase MW, Hoot SB, Morton CM, Soltis DE,
Bayer C, Fay MF, de Bruijn AY, Sullivan S, Qiu Y-L.
2000. Phylogenetics of flowering plants based on a
combined analysis of plastid atpB and rbcL sequences.
Systematic Biology 49: 306–362.
Soltis DE, Soltis PS, Chase MW, Mort ME, Albach DC, Zanis
M, Savolainen V, Hahn WH, Hoot SB, Prince LM, Kress
WJ, Nixon KC, Farris J S. 2000. Angiosperm phylogeny
inferred from 18S rDNA, rbcL, and atpB sequences.
Botanical Journal of Linnean Society 133: 381–461.
Steward AN. 1930. The Polygonaceae of Eastern Asia.
Contributions from the Gray Herbarium of Harvard
University 5: 1–129.
Swofford DL. 1998. PAUP*: phylogenetic analysis using
parsimony (* and other methods). Version 4.0. Sunderland,
Massachusetts: Sinauer Associates.
Yasui Y, Ohnishi O. 1998a. Interspecific relationships in
Fagopyrum (Polygonaceae) revealed by the nucleotide
sequences of the rbcL and accD genes and their intergenic
region. American Journal of Botany 85: 1134–1142.
Yasui Y, Ohnishi O. 1998b. Phylogenetic relationships among
Fagopyrum species revealed by nucleotide sequences of
the ITS region of the nuclear rRNA gene. Genes and
Genetic Systems 73: 201–210.
Zhang X-P (张小平), Zhou Z-Z (周忠泽). 1998. A study on
pollen morphology and its phylogeny of Polygonaceae in
China (中国蓼科花粉的系统演化 ). Hefei: Press of
University of Science and Technology of China.
Zhou Z-Z (周忠泽), Xu R-X (许仁鑫), Zhuang Y-L (庄永龙),
Lin Z-Q ( 林中清 ). 2000. Studies on pollen exine
ultrastructure of the Polygonaceae. Acta Phytotaxonomica
Sinica (植物分类学报) 38: 446–451.
Zhou Z-Z (周忠泽), Zhao Z-C (赵佐成), Wang X-Y (汪旭莹),
Xu R-X (许仁鑫 ), Li Y-C (李玉成 ). 2003. Pollen
morphology, tepal and fruit microcharacteristics of the
genus Fagopyrum Mill. from China. Acta Phytota-
xonomica Sinica (植物分类学报) 41: 63–78.
SUN et al.: Reappraisal of the generic status of Pteroxygonum

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对翼蓼(蓼科)属级位置的重新探讨
孙 伟 周忠泽* 刘明珍 万和文 董 祥
(安徽大学生命科学学院, 安徽省工程与生物技术重点实验室 合肥 230039)

摘要 通过对翼蓼Pteroxygonum giraldii Damm. & Diels及相关属(蓼属Polygonum、何首乌属Fallopia、虎杖属Reynoutria、荞
麦属Fagopyrum和金线草属Antenoron)的形态观察、果实解剖学观察、花被片脉序观察、花粉形态、核型分析, 以及ITS序列
的分析确定了翼蓼和荞麦F. esculentum Moench较远的亲缘关系。其中我们发现翼蓼果实基部有三个角状物明显不同于其他属
果实的形态特征。翼蓼外果皮明显加厚, 并有零星散布的波状内腔, 而荞麦的外果皮很薄, 细胞不等径, 中果皮极厚。以上证
据证明了翼蓼与荞麦属亲缘关系较远。在观察荞麦属和翼蓼的花被片脉络时发现了两种不同的脉序类型, 符合将荞麦属分为
两个组的划分。翼蓼花被片脉序为三出状, 支持将翼蓼归为Persicarieae族。对翼蓼及荞麦属植物的花粉进行比较后, 发现荞
麦属植物的花粉网孔有明显的内凹穿孔而翼蓼却没有, 结果表明二者亲缘关系较远。通过对nrDNA ITS区域序列分析得出翼
蓼及相关属为一个单系类群, 含有两个稳定的分支: 第一个分支由蓼属(萹蓄组sect. Avicularia)、何首乌属、虎杖属的植物组
成, 第二个分支由蓼属(刺蓼组sect. Echinocaulon、蓼组sect. Polygonum、分叉蓼组sect. Aconogonon、拳参组sect. Bistorta、翼
蓼和荞麦属植物组成。同时第二个分支又分成了两个亚分支, 蓼属(刺蓼组、蓼组、分叉蓼组、拳参组)和翼蓼属Pteroxygonum
植物属于第一个亚支而荞麦属植物属于第二个亚支。结果支持翼蓼不属于荞麦属的范畴。实验结果显示翼蓼是个单型属, 属
于Persicarieae族。
关键词 果实解剖; 花被片形态; 花粉形态; ITS; 翼蓼属; 蓼科