Pollen Characteristics of Polygala, Salomonia and ... - ThaiScience

The Natural History Journal of Chulalongkorn University 9(1): 27-34, April 2009 

©2009 by Chulalongkorn University 

Pollen Characteristics of Polygala, Salomonia and Xanthophyllum 

(Polygalaceae) in Thailand 

PUNTIWA KRACHAI 1 , PRANOM CHANTARANOTHAI 1* AND NARUMOL PIWPUAN 2 

1 Applied Taxonomic Research Center, Department of Biology, Faculty of Science, 

Khon Kaen University, Khon Kaen 40002, Thailand 

2 Department of Science and Technology, Nong Khai Campus, Khon Kaen University, 

Nong Khai 43000, Thailand 

ABSTRACT.– The pollen morphology was investigated in 20 species of Polygala, 

Salomonia and Xanthophyllum (Polygalaceae) by means of light microscopy 

(LM) and scanning electron microscopy (SEM). Characteristics regarded as 

particularly distinctive include pollen symmetry, polar type and the 

sculpturing pattern at the apocolpium. Based on pollen morphology, 

Xanthophyllum should not be raised up to the level of a distinct familial taxa. 

KEY WORDS: Pollen, Polygala, Salomonia, Xanthophyllum, Thailand 

INTRODUCTION 

The family Polygalaceae belongs to 

order Polygales and is comprised of 18 

genera with ca. 1,000 species worldwide. 

Most species are widely represented in the 

temperate and tropical regions, and the 

family is divided into three tribes, 

Polygaleae, Moutabeae and Xanthophylleae 

(Hutchinson, 1967). The last tribe is 

considered to be a separate family, 

Xanthophyllaceae, by Cronquist (1981), 

whereas Heywood et al. (2007) classified 

the Polygalaceae into four tribes viz 

Polygaleae, Carpolobieae, Moutabeae and 

Xanthophylleae. Only representative species 

from the tribes Polygaleae and 

Xanthophylleae are present in Thailand, 

* Corresponding author: 

Tel: (6643)-342-908 

Fax: (6643)-364-169 

Email: pranom@kku.ac.th 

with five genera and 36 species. Within 

Thailand the Polygaleae tribe contains four 

genera: Epirixanthes, Polygala, Salomonia 

and Securidaca, whilst the Xanthophylleae 

has one genus, Xanthophyllum (Pendry, 

2001). Some species of Thai Polygalaceae 

have medicinal uses, such as Polygala 

chinensis, Salomonia cantoniensis, S. 

longicilliata and Xanthophyllum lanceatum 

(Mahidol University Foundation, 2000). 

The pollen morphology of Polygalaceae 

has not been extensively examined. Only a 

few species were described by Erdtman 

(1966), Paiva and Santos Dias (1990) and 

Furness and Stafford (1995). Pollen grains of 

Polygalaceae are zonocolporate, suboblate to 

subprolate and often with obscure exine 

stratification (Erdtman, 1966). The pollen 

morphology of the family has never been 

studied in Thailand and, therefore, the aims 

of the present work are to classify, describe

28 

and illustrate the pollen morphology of the 

Thai Polygalaceae. 

MATERIALS AND METHODS 

The pollen from 20 taxa of Polygalaceae 

in Thailand were collected in the field by the 

third author and examined by light 

microscopy (LM) and scanning electron 

microscopy (SEM). The pollen was prepared 

according to the standard method of 

acetolysis (Erdtman, 1966). For LM, pollen 

was mounted in silicone oil and sealed with 

paraffin. Measurements were based on 15 

pollen grains per species. The polar axis (P), 

equatorial axis (E), exine thickness (EX), 

NAT. HIST. J. CHULALONGKORN UNIV. 9(1), APRIL 2009 

TABLE 1. Pollen morphology of Thai Polygalaceae (Apo = apocolpium, CL = colpi length, E =equatorial axis, 

Ex = exine thickness, Me = mesocolpium, SP = sculpturing pattern, P = polar axis, ret = reticulate, retD = 

reticulate with depression, rug = rugulate). 

Taxa Type Polarity Symmetry Amb shape P (µm) 

Tribe Polygaleae 

Polygala 

Polygala section Pseudosemeiocardium 

P. cardiocarpa G-I heteropolar bilateral oblate oblate 23-29 (26.3±1.9) 

P. malesiana G-I heteropolar bilateral oblate oblate 25-30 (27.8±1.6) 

P. umbonata G-I heteropolar bilateral oblate oblate 13-20 (17.9±1.7) 

Polygala section Chamaebuxus 

P. arillata G-IITIIA isopolar radial circular suboblate 42-51 (46.1±2.3) 

P. karensium G-I heteropolar bilateral oblate oblate 34-46 (41.0±3.4) 

P. venenosa G-IITIIB isopolar radial circular subprolate 50-64 (56.1±4.4) 

Polygala section Polygala 

P. chinensis G-IITIIA isopolar radial circular subprolate 29-39 (33.8±2.6) 

P. erioptera G-IITI isopolar radial circular oblate-spheroidal 19-27 (22.0±2.0) 

P. longifolia G-IITIIA isopolar radial circular prolate 29-55 (39.0±8.8) 

P. persicariifolia G-IITI isopolar radial circular oblate-spheroidal 32-38 (34.6±1.7) 

P. polifolia G-IITI isopolar radial circular prolate 31-44 (40.8±4.0) 

P. triflora G-IITIIA isopolar radial circular subprolate 37-46 (40.8±3.9) 

Salomonia 

S. cantoniensis G-IITI isopolar radial circular subprolate 30-39 (33.0±2.6) 

S. ciliata G-IITI isopolar radial circular oblate-spheroidal 33-40 (35.0±2.0) 

S. kradungensis G-IITI isopolar radial circular oblate-spheroidal 37-48 (41.3±3.0) 

S. longiciliata G-IITI isopolar radial circular oblate-spheroidal 27-35 (31.2±2.8) 

S. thailandica G-IITI isopolar radial circular oblate-spheroidal 35-48 (40.4±3.2) 

Tribe Xanthophylleae 

Xanthophyllum 

X. ellipticum G-IITIIB isopolar radial circular prolate-spheroidal 26-33 (28.8±1.7) 

X. geesinkii G-IITIIB isopolar radial circular suboblate 22-29 (24.8±1.8) 

X. lanceatum G-IITIIB isopolar radial circular oblate-spheroidal 25-33 (28.2±2.8) 

colpus length (CL) and number of colpi (NC) 

were recorded. For SEM, acetolysed pollen 

grains were suspended in a drop of absolute 

alcohol, then transferred to stubs and coated 

with gold-palladium mixture. SEM 

micrographs were taken with Leo 1450VP 

SEM. Descriptive terminology is according 

to Erdtman (1966). 

RESULTS 

General pollen description 

The family Polygalaceae pollen is 

monad, isopolar or heteropolar, radially or 

bilaterally symmetric, zonocolporate, small 

to large-sized (P =13 - 64 µm, E = 20 - 78 

µm) and oblate to prolate in shape. The

KRACHAI ET AL. — POLYGALACEAE POLLENS IN THAILAND 29 

TABLE 1. Cont. 

E (µm) 

Number of 

apertures 

exine stratification is mostly obscure, 1 - 10 

µm in thickness. The pollen has a psilate 

surface on the mesocolpium. Three exine 

sculpturing patterns at the apocolpium are 

present within the genera studied. All 

species in the Polygala section 

Pseudosemeiocardium and P. karensium 

have aperturoid depression, whereas psilate 

is found in all species of P. arillata, P. 

chinensis, P. longifolia, P. triflora, P. venenosa 

and Xanthophyllum, and reticulate or 

reticulate-rugulate is found in most species 

of Polygala section Polygala. The pollen 

morphology is summarized in Table 1. 

Polygala: The pollen grains are mostly 

oblate or subprolate, less frequently oblatespheroidal, 

prolate or suboblate, P = 13 - 64 

µm; E = 20 - 78 µm. The number of 

CL (µm) Ex (µm) 

SP 

Me Apo 

44-58 (51.0±3.8) 20-24 (21.8±1.3) 12-16 (13.8±1.3) 2-3 (2.1±0.3) psilate retD 

48-66 (54.1±4.4) 24-29 (27.6±1.4) 13-18 (15.2±1.7) 2-3 (2.2±0.4) psilate retD 

30-37 (34.3±2.3) 22-27 (24.4±1.6) 7-11 (8.8±1.01) 1-2 (1.8±0.2) psilate retD 

49-57 (53.4±2.8) 16-20 (17.3±0.9) 30-38 (33.6±1.8) 6-10 (7.1±1.3) psilate psilate 

58-78 (67.8±7.2) 19-21 (20.2±0.6) 19-30 (24.7±4.0) 3-5 (4.3±0.6) psilate retD 

40-49 (44±3.2) 11-14 (12.4±1.0) 33-40 (35.8±2.3) 3-6 (4.4±0.9) psilate psilate 


20-28 (23.0±2.0) 17-22 (19.0±1.7) 16-22 (17.9±1.4) 3-5 (4.0±0.5) psilate ret 


31-40 (34.6±3.1) 15-18 (16.6±0.8) 23-29 (25.0±1.5) 4-7 (5.2±0.7) psilate ret 

22-28 (24.0±1.6) 25-30 (27.2±1.4) 20-32 (26.6±3.6) 5-7 (5.8±0.6) psilate ret 


23-30 (25.3±2.0) 18-23 (21.1±1.1) 19-28 (23.0±2.6) 3-6 (5.0±0.8) psilate ret-ru 

31-41 (35.9±2.7) 12-16 (13.9±1.0) 20-26 (23.0±2.0) 4-7 (5.8±0.9) psilate ret-ru 

33-48 (42.7±4.7) 12-14 (12.5±0.6) 21-33 (27.93±3.0) 5-8 (6.2±1.0) psilate ret-ru 

28-38 (33.3±2.6) 10-13 (12.1±0.6) 17-23 (20.2±1.5) 4-7 (5.0±0.8) psilate ret-ru 

36-50 (41.4±3.9) 11-13 (12.4±0.6) 20-31 (25.3±3.5) 5-9 (6.7±1.1) psilate ret-ru 



26-37 (31.5±3.4) 9-11 (9.7±0.7) 19-25 (20.9±1.9) 2-5 (3.4±0.7) psilate Psilate 

apertures varies from 11 - 30 with 5 - 40 µm 

long colpiand 1 - 10 µm thick exines (Fig. 

1A - L). 

Salomonia: The pollen grains are mostly 

oblate-spheroidal, rarely subprolate, P = 27 - 

48 µm; E = 23 - 50 µm. The number of 

apertures is 10 - 23 with 17 - 33 µm long 

colpi and 3 - 9 µm thick exines (Fig. 1M - 

Q). 

Xanthophyllum: The pollen grains are 

oblate-spheroidal, suboblate or prolatespheroidal, 

P = 22 - 33 µm; E = 23 - 37 µm. 

The number of apertures is 7 - 11 with 16 - 

25 µm long colpi and 2 - 5 µm thick exines 

(Fig. 1R - T).

30 


FIGURE 1. LM micrographs showing Polygalaceae pollen in polar view and equatorial view. A) P. arillata, B) P. 

cardiocarpa, C) P. chinensis, D) P. erioptera, E) P. karensium, F) P. longifolia, G) P. malesiana, H) P. persicariifolia, 

I) P. polifolia, J) P. triflora, K) P. umbonata, L) P. venenosa, M) S. cantoniensis, N) S. ciliata, O) S. kradungensis, P) 

S. longiciliata, Q) S. thailandica, R) X. ellipticum, S) X. geesinkii, T) X. lanceatum. Scale bars = 10 µm.


DISCUSSION AND CONCLUSION 

The present study shows that the main 

characteristic features of pollen of Polygala, 

Salomonia and Xanthophyllum are isopolar, 

radially symmetric, suboblate to subprolate 

in shape, a zonocolporate aperture in all 

genera, with a variable number of apertures 

between and within species. The exine 

sculpturing pattern is psilate on the 

mesocolpium and with or without 

depression at the poles. These characters 

agree well with those reported earlier for 

Polygalaceae (Erdtman, 1966; Paiva & 

Santos Dias, 1990 and Furness & Stafford, 

1995). Furthermore, a heteropolar grain, 

bilateral symmetry, oblate or prolate in 

shape and reticulate or reticulate-rugulate 

sculpturing pattern at apocolpium are 

additional informative characters that have 

never been reported previously 

The pollen shape of all species studied 

was mostly circular in polar view and 

oblate-spheroidal in equatorial view, but 

subprolate, suboblate, prolate or prolatespheroidal 

shapes can also be found in a few 

species. 

Two pollen groups can be established on 

the basis of the polar type and pollen 

symmetry. 

Group I: This group has heteropolar 

grain and bilateral symmetry. The pollen 

morphology of this group is represented in 

all species of the Polygala section 

Pseudosemeiocardium (P. cardiocarpa, P. 

malesiana and P. umbonata) and P. 

karensium in the section Chamaebuxus (Fig. 

2A - D), P = 13 - 46 µm, E = 30 - 78 µm. 

The smallest size was found in P. umbonata 

(P = 13 - 20 µm, E = 30 - 37 µm), and the 

largest in P. karensium (P = 34 - 46 µm, E = 

58 - 78 µm). The number of apertures varied 

from 19 to 29, the exine is 1-5 µm thick 

with a psilate sculpturing pattern on the 

mesocolpium but a reticulate sculpturing 

pattern with depression at the apocolpium. 

The members of this group are also 

supported by anatomical studies. Piwpuan 

(2007) reported that the leaf surface of this 

group has a unicellular trichome which is 

spine-like, but this does not agree well with 

the morphological classification. 

Group II: This group has an isopolar 

grain and radial symmetry, and can also be 

divided into 2 types based on the 

sculpturing pattern at the apocolpium. 

Type I: This type is characterized by a 

reticulate or a reticulate-rugulate 

apocolpium. The pollen is oblate-spheroidal 

to prolate in shape (P = 19 - 48 µm, E = 20 - 

50 µm). The number of apertures varies 

from 10 to 30 with a 3 - 9 µm thick exine 

that has a psilate sculpturing pattern on the 

mesocolpium and a reticulate or reticulaterugulate 

pattern at the apocolpium. P. 

polifolia tends to have more apertures than 

the other members of this type (25-30 vs 10- 

23). 

This type comprises all members of 

Salomonia and three species of Polygala, P. 

erioptera, P. persicariifolia and P. polifolia 

(Fig. 2E - L). 

Type II: This type is characterized by a 

psilate apocolpium. The pollen is suboblate 

to prolate in shape (P = 22 - 64 µm, E = 22 - 

57 µm). The number of apertures is 7 - 27 

and the exine is 2 - 10 µm thick. Two 

subtypes can be established based on the 

number of apertures. 

Subtype A: This subtype has 16 - 27 

apertures and contains P. arillata, P. 

chinensis, P. longifolia and P. triflora. P. 

longifolia has the shortest colpi which 

ranges from 5 - 10 µm (Fig. 3A-D). 

Subtype B: This subtype has a small 

number of apertures, 7 - 14, and contains all

32 

the examined species of Xanthophyllum plus 

P. venenosa. (Fig. 3E - H). The presence of 

sclereid cells on the ground tissue of the 


FIGURE 2. SEM micrographs of pollen. Group I (A-D) and Group II Type I (E-L): A) P. cardiocarpa, 

equatorial view showing reticulate with depression at apocolpia and apertures. B) P. karensium, subequatorial 

view showing reticulate with depression at apocolpium and apertrues. C) P. malesiana, equatorial view 

showing reticulate with depression at apocolpia and apertures. D) P. umbonata, subpolar view showing 

reticulate with depression at apocolpium and apertures. E) P. erioptera, subequatorial view showing reticulate 

apocolpium and apertures. F-G) Equatorial view showing apertures and reticulate apocolpia and apertures, F) 

P. persicariifolia. G) P. polifolia. H) S. cantoniensis, subpolar view showing reticulate-rugulate apocolpium. 

I) S. ciliata, equatorial view showing apertures and reticulate-rugulate apocolpium. J-L.) Subpolar view 

showing reticulate-rugulate apocolpium and apertures, J) S. kradungensis, K) S.longiciliata, L) S. thailandica. 

Scale bars = 10 µm. 

stem and a similar pattern of the vascular 

tissues in the floral part supports the


FIGURE 3. SEM micrographs of pollen. Group II Type II subtype A (A-D) and Group II Type II subtype B 

(E-H): A) P. arillata, subequatorial view showing psilate apocolpia and apertures. B-C) Subequatorial view 

showing psilate apocolpia and apertures, B) P. chinensis, C) P. longifolia. D) P. triflora, equatorial view 

showing psilate apocolpia and apertures. E) P. venenosa, polar view showing psilate apocolpium. F) X. 

ellipticum, subpolar view showing psilate apocolpium. G) X. geesinkii, equatorial view showing apertures and 

psilate at apocolpia. H) X. lanceatum, subpolar view showing psilate apocolpium. Scale bars = 10 µm. 

grouping of P. venenosa and Xanthophyllum 

(Piwpuan, 2007; Eriksen, 1993). 

The palynological and anatomical studies 

suggest that Xanthophyllum should be treated 

as a genus within Polygalaceae. However, 

more taxa need to be examined and 

alternative techniques, such as perhaps 

molecular systematic approaches, are needed 

to clarify the infrageneric taxa of this family. 

ACKNOWLEDGEMENTS 

This work was supported by the Applied 

Taxonomic Research Center, Department of 

Biology, Faculty of Science, Khon Kaen 

University.

34 

LITERATURE CITED 

Cronquist, A. 1981. An integrated system of 

classification of flowering plants. Columbia 

University Press, New York. 

Erdtman, G. 1966. Pollen Morphology and Plant 

Taxonomy Angiosperms. Hafner Publishing 

Company, New York. 

Eriksen, B. 1993. Floral anatomy and morphology in 

the Polygalaceae. Plant Systematics and Evolution, 

186: 17-32. 

Furness, S.H. and Stafford, P.J. 1995. The Northwest 

European Pollen Flora, 55; Polygalaceae.Review of 

Palaeobotany and Palynology, 88: 61-82. 

Heywood, V.H., Brummitt, R.K., Culham, A. and 

Oseberg, O. 2007. Flowering Plant Families of the 

World. Royal Botanic Gardens, Kew. 

Hutchinson, J. 1967. The Genera of Flowering Plants 

(Angiospermae): Dicotyledons, vol. II. Oxford 

University Press. 

Mahidol University Foundation. 2000. Encyclopedia of 

herbal medicine, vol. 4 Kok Ya Esarn. 1 st ed. 

Amarin Printing and publishing Public Co. Ltd., 

Bangkok. 

Paiva, J. and Santos Dias, J.D. 1990. The pollen grain 

of Polygala fruticosa Berg. (Polygalaceae). Anales 

del Jardín Botánico de Madrid, 47(2): 377-385. 

Pendry, C.A. 2001. Polygalaceae. In: Flora of Thailand. 

T. Santisuk and K. Larsen (Eds.). Prachachom Co. 

Ltd., Bangkok. Vol. 7, part 3, pp. 498-538. 

Piwpuan, N. 2007. Comparative Anatomy of 

Polygalaceae in Thailand. Master of Science Thesis 

in Biology, Graduate School, Khon Kaen 

University, Thailand. 

Received: 24 November 2008 

Accepted: 17 January 2009 


APPENDIX 

SPECIMENS EXAMINED 

The species are enumerated in 

alphabetical order. All specimens examined 

are deposited at Khon Kaen University 

Herbarium (KKU); Polygala arillata Buch.- 

Ham. ex D.Don, Narumol 24. -P. 

cardiocarpa Kurz, Narumol 101. -P. 

chinensis L., Narumol 21. -P. erioptera DC., 

Narumol 97. -P. karensium Kurz, Narumol 

19. -P. longifolia Poir., Narumol 23. -P. 

malesiana Adema, Narumol 60. -P. 

persicariifolia DC., Narumol 95. -P. polifolia 

C.Presl, Narumol 61. -P. triflora L., Narumol 

81. -P. umbonata Craib, Narumol 90. -P. 

venenosa Juss. ex Poir., Narumol 42. - 

Salomonia cantoniensis Lour., Narumol 26. - 

S. ciliata (L.) DC., Narumol 59. -S. 

kradungensis H. Koyama, Narumol 88. -S. 

longiciliata Kurz, Narumol 22. -S. 

thailandica H.Koyama, Narumol 80. - 

Xanthophyllum ellipticum Korth. ex Miq., 

Narumol 50. -X. geesinkii Meijden, Narumol 

37. -X. lanceatum (Miq.) J.J.Sm., Narumol 

36.

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