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0Annals of Agricultural Science (2014) 59(2), 229-238
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Faculty of Agriculture, Ain Shams University Annals of Agricultural Science
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Seed morphology and seed coat anatomy of some ck»^ species of Apocynaceae and Asclepiadaceae
Dalia G. Gabr *
Department of Botany and Microbiology, Faculty of Science (Girls Branch), Al-Azhar University, Cairo, Egypt
Received 20 July 2014; accepted 12 November 2014 Available online 10 December 2014
KEYWORDS
Apocynaceae; Asclepiadaceae; Identification; Seed morphology; Seed coat anatomy; SEM
Abstract Seed shape, dimensions, surface texture and sculpture, hilum shape and position were recorded for seven species of each of the Apocynaceae and Asclepiadaceae by using light microscope (LM) and scanning electron microscope (SEM). Seven patterns were recognized based on surface sculpturing pattern: reticulate (with five subtypes), striate, ruminate, papillate, colliculate, aculeate and rugose.
Anatomical investigation using light microscope showed that the hypodermis is present in the outer integument of two species and absent in the rest. The inner integument is recorded two types. The data proved useful in the construction of a bracketed key to the species. The potential taxo-nomic value of the recorded characters is indicated by the richness of variation recorded in the limited sample of genera and species.
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Introduction
The Apocynaceae and Asclepiadaceae are relatively large families comprising a total of approximately 5000 species of mainly tropical or subtropical plants with abundant latex. The seed features of the two families include wings, comas, and arils.
The morphology of seed coat is usually stable and is little influenced by external environmental conditions while the seeds develop and ripen within the fruit (Heywood, 1971; Cole and Behnke, 1975; Barthlott, 1981). Therefore seed characters can provide useful data in the delimitation and identification of species. The morphologic features of different seed structures
* Tel.: +20 01002454862. E-mail address: Dalia_goda@hotmail.com. Peer review under responsibility of Faculty of Agriculture, Ain-Shams University.
provide a wide range of characters which can play an important role on the identification of taxa (Vaughan, 1968) and have traditionally been used to solve systematic and phylogenetic problems. Micromorphology and ultra-structural data have contributed useful information for evolution and classification of seed plants and play an important role in the modern synthetic systems of angiosperms (Dahlgren, 1980). Several studies focused on intragenic seed coat variation (Juan et al., 2000; Segarra and Mateu, 2001) or on variation among several closely related genera (Zainhasan and Lester, 1990; Karam, 1997; Kanak Sahai et al., 1997; Koul et al., 2000; Abdel Khalik and Vander Maesen, 2002; Al-Gohary and Mohamed, 2007; Abdel Khalik, 2013). Scanning electron microscopy (SEM) provides deeper insight where gross morphology proves insufficient to analysis seed coat structure and surface sculpture. These two aspects are of a great taxonomic value at generic and infra-generic status (Brisson and Peterson, 1976, 1977).
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Very little research has been undertaken on the seed coat surface of the species of Apocynaceae and Asclepiadaceae as (Pichon, 1948, 1949; Leeuwenberg, 1994; Omlor, 1998; Dlcdm et al., 2010 and Kumar et al., 2011). In Egypt only a few Egyptian species have been worked out for seed coat surface as; Al Nawaihi et al., 2006 and the anatomy are not yet correctly projected. The present work examined the morphological and micro-morphological characteristics of the seeds for 14 species in Egypt, in a search for taxonomic characters useful in distinguishing of the species.
Materials and methods
The present study included seeds of seven species of Apocyna-ceae and seven species of Asclepiadaceae collected fresh from different localities in Egypt (Table 1). The materials studied were identified by means of comparison with specimens kept in the herbarium of the Agricultural Museum (CAIM). In addition, keys of Bailey (1916), Lindley (1932), Metcalfe and Chalk (1979), Hutchinson and Dalziel (1963), Tackholm (1974), Davis (1975), Pandey (1997), Endress and Bruyns (2000) and Boulos (2000). Reference herbarium specimens of studied species were prepared and kept in the herbarium of Botany and Microbiology Department, Faculty of Science (Girls Branch) Al-Azhar University. For seed morphology, five to seven seeds were investigated to record their dimensions, shape, color and surface texture. Details of seed sculpture were examined by a JEOL JSM - 5500 scanning electron microscope operated at an accelerated voltage of 20 kV and photographed. The terminology of Barthlott (1981, 1990) and Stearn (1992) was adopted to describe the SEM aspects of the seed coat.
For seed anatomy matured seed was soaked in boiling water, then hand section at 20-30 pm in thickness take place. The sections were stained according to Dilcher (1974) in safranin (1% solution in 50% ethanol) and light green (1% solution in 96% ethanol) then photographed.
Results and discussion
Examination of available specimens yielded a wealth of information concerning seed morphology, sculpture of seed surface and anatomy of seed coat. Variation in these three aspects among the species is listed in Table 2 and recorded comparatively for individual species in Table 3. Although the characters and their states are self explanatory, they are illustrated in Plates 1-3 for further clarification. Most of the characters and their states as defined in Table 2 are recorded for the first time for the species included in the present study.
The data recorded in Table 3 were used to construct the following bracketed key to the 14 species of Apocynaceae and Asclepiadaceae that it might help in the confirmation of their identification.
Table 1 Collection data of the species included in the present study; all localities are in Egypt.
Family
Species
Locality and date
Apocynaceae Acokanthera spectabilis Hook.
Carissa spinarum L. Thevetia peruviana (Pers.) K. Schum. Vinca rosea L. Alstonia scholaris (L.) R. Br.
Nerium oleander L. Mascarenhasia elastica K. Schum.
Asclepiadaceae Leptadenia arborea (Forssk.) Schweinf. Leptadenia pyrotechnica (Forssk.) Decne. Calotropis procera (Aiton) W. T. Aiton. Cynanchum acutum L. Solenostemma argel (Delile) Hayne. Asclepias curassavica L.
Cryptostegia grandiflora R.Br.
El-Orman Garden, 3/ 2009
The Zoo, 3/2009 Agriculture Museum Garden, 3/2009 The Zoo, 3/2009 The Zoo, 3/2009
El-Kobba Palace, 3/2009 Asswan Botanical Garden, 4/2009
Asswan, 4/2010
Wadi Hagol, 3/2010
Al-Azhar University, 6/ 2009
El-Fayoum, 3/2009 Asswan, 4/2010
Asswan Botanical Garden, 4/2009 Agriculture Museum Garden, 3/2009
1. Seeds folded 2
1. Seeds flat
2. Seed elliptic and seed coat Carissa spinarum
reticulate-undulate
2. Seeds flask-shaped; seed coat Solenostemma argel
irregular reticulate...
3. Seed winged 4
3. Seed wingless
4. Seed texture hairy with Calotropis procera
papillate coat
4. Seed texture not hairy; coat
not papillate
5. Seed texture smooth and seed Leptadenia pyrotechnica
coat reticulate
5. Seed texture tuberculate and
seed coat not so
6. Seed coat ruminate Leptadenia arborea
6. Seed coat colliculate Cynanchum acutum
Seed globose 3
7. Seed flattened 5
Seed color off white and seed Thevetia peruviana
coat striate
8. Seed color otherwise and seed
coat reticulate
9. Seed color brown and seed size Acokanthera spectabilis
more than 10 mm
9. Seed color black and seed size Vinca rosea
1-2 mm
10. Seed texture hairy or warty
10. Seed texture tuberculated
11. Seed texture hairy and seed Nerium oleander
coat reticulate-rugose...
11. Seed texture warty and seed Asclepias curassavica
aculeate
12. Seed oblong and coma Alstonia scholaris
persistent
12. Seed elliptic or long ovate and
coma deciduous
13. Seed elliptic and seed coat Mascarenhasia elastica
reticulate-verruculate
13. Seed long ovate; seed coat Cryptostegia grandiflora
rugose
Table 2 List of characters of seed morphology and anatomy recorded comparatively for 14 species of Apocynaceae and
Asclepiadaceae. Illustrations of character-states are shown in figures of Plates 1-3. Distribution of characters and character-states
among the species is given in Table 3.
No. Part Character Character-states and symbols Illustrations
Plate Figure(s)
1 Seed Color 1 - Brown 1 1
2 - Off white 1 3
3 - Black 1 4
2 Seed Texture 1 - Warty 1 13
2 - Tuberculate 1 5
3 - Irregular striated 1 3
4 - Hairy 1 10
5 - Smooth 1 9
3 Seed Outline 1 - Elliptic 1 7
2 - Ovate 1 8
3 - Oblong 1 5
4 - Flask-shaped 1 12
4 Seed Shape 1 - Globose 1 1
2 - Flattened 1 14
5 Seed Margin 1 - Wingless 1 3
2 - Winged 1 10
3 - Folded 1 2
4 - Hairy 1 5
6 Seed Size 1 - 10-14 mm 1 1
2 - 4-8 mm 1 8
3 - 1-2 mm 1 4
7 Hilum Position 1 - Terminal 1 3
2 - Central 1 2
8 Hilum Shape 1 - Oblong 1 1
2 - Elliptic 1 5
3 - Conical 1 3
4 - Linear 1 14
5 - Oblong-ovate 1 10
9 Hilum Level 1 - Depressed 1 2
2 - Semi-depressed 1 7
3 - Elevated 1 4
4 - Superficial 1 14
10 Coma Color 1 - Brown 1 5
2 - Off-while 1 14
3 - Absent 1 1
11 Coma Duration 1 - Deciduous 1 10
2 - Persistence 1 6
3 - Absent 1 3
12 Coma PositionA 1 - Terminal 1 14
2 - Peripheral 1 5
3 - Covering all seed surface 1 6
4 - Absent 1 2
13 Seed surface Sculpture 1a - Reticulate-regular 2 1
1b - Reticulate-undulate 2 2a
1c - Reticulate-rugose 2 6
1d - Reticulate-verruculate 2 7
1e - Reticulate-irregular 2 12a
2 - Striate 2 3
3 - Ruminate 2 8a
4 - Papillate 2 10a
5 - Colliculate 2 11a
6 - Aculeate 2 13
7 - Rugose 2 14
(continued on next page)
Table 2 (continued)
No . Part Character Character-states and symbols Illustrations
Plate Figure(s)
14 Seed coat Anticlinal walls: shape 1 - Wavy 2 1
2 - Undulate 2 10a
3 - Undulate with hairs 2 6
4 - Spiral 2 3
15 Seed coat Anticlinal walls: thickness 1 - Thick 2 2a
2 - Thin 2 5
16 Seed coat Anticlinal walls: level 1 - Raised 2 12a
2 - Grooved 2 11a
17 Seed coat Periclinal walls: level 1 - Concave 2 6
2 - Convex 2 14
18 Seed coat Periclinal walls: texture 1 - Smooth-finely striated 2 1
2 - Smooth 2 2a
3 - Smooth with wax 2 6
4 - Tuberculate 2 10a
5 - ±Worty 2 12a
19 Seed wing SculptureA 1 - Reticulate 2 9b
2 - Reticulate foveate 2 2b
3 - Tuberculate 2 10b
4 - Colliculate 2 11b
5 - Colliculate with secondary roseate structure 2 12b
20 Seed wing Anticlinal walls: shapeA 1 - Irregular round 2 2b
2 - Round-polygonal 2 8b
3 - Undulate 2 9b
4 - ± Round 2 11b
5 - Round 2 12b
21 Seed wing Anticlinal walls: thicknessA 1 - Thick 2 2b
2 - Thin 2 12b
22 Seed wing Anticlinal walls: levelA 1 - Raised 2 8b
2 - Grooved 2 10b
23 Seed wing Periclinal walls: levelA 1 - Concave 2 2b
2 - Convex 2 12b
24 Seed wing Periclinal walls: textureA 1 - Smooth 2 12b
2 - Smooth with wax 2 11b
3 - Tuberculate 2 10b
4 - Worty with wax 2 2b
25 Seed coat anatomy Outer integument: cuticle thickness 1 - Thick 3 2
2 - Thin 3 1
26 Seed coat anatomy Outer integument: cuticle surface 1 - Smooth 3 10
2 - Warty 3 6
27 Seed coat anatomy Epidermis 1 - Radial 3 4
2 - Tangential 3 6
3 - Radial + tangential 3 7
28 Seed coat anatomy Hypodermis 1 - Present 3 10
2 - Absent 3 12
29 Seed coat anatomy Inner integument 1 - Layers of crushed parenchyma cells 3 1
2 - One layer of thick square cell followed 3 8
by crushed parenchyma cells
30 Seed coat anatomy Endosperm shape 1 - Angular 3 1
2 - Elongated 3 2
3 - Round-polygonal 3 4
4 - Round 3 10
5 - Polygonal 3 13
31 Seed coat anatomy Endosperm thickness 1 - Thick 3 8
2 - Thin 3 1
A Inapplicable state if part is absent.
Table 3 Comparative recording of the [31] characters listed in Table 2 for seven species of each of the Apocynaceae and Asclepiadaceae. Serial numbers of characters and symbols denting character-states are those assigned to them in Table 2.
Species
Characters
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19a 20a 21a 22a 23a 24a 25 26 27 28 29 30 31
Acokanthera spectabilis 1 2 1 1 1 2 1 3 3 3 4 1a 1 2 1 1 1 - - - - - - 2 1 3 2 1 1 2
Carissa spinarum 2 1 2 3 2 2 2 1 3 3 4 1b 2 1 1 1 2 2 1 1 1 1 4 1 1 1 2 1 2 1
Thevetia peruviana 3 3 1 1 1 1 3 4 3 3 4 2 4 2 1 1 2 - - - - - - 2 1 1 2 1 3 2
Vinca rosea 2 2 1 1 3 2 2 3 3 3 4 1a 2 2 1 1 2 - - - - - - 2 1 1 2 1 3 2
Alstonia scholaris 2 3 2 4 2 2 2 2 1 2 2 1a 2 2 1 1 2 - - - - - - 1 1 1 2 1 3 2
Nerium oleander 4 2 2 1 2 2 2 3 1 2 3 1c 3 1 1 1 3 - - - - - - 2 2 2 2 1 3 1
Mascarenhasia elastica 2 1 2 1 2 2 1 2 1 1 1 1d 3 1 1 1 5 - - - - - - 1 2 3 2 1 3 1
Leptadenia arborea 2 2 2 2 2 2 4 4 2 1 1 3 3 2 1 1 1 2 2 1 1 1 1 1 2 3 2 3 1
Leptadenia pyrotechnica 5 2 2 2 1 2 4 2 2 1 1 1a 2 2 1 1 4 1 3 2 1 1 3 2 1 3 2 1 3 2
Calotropis procera 4 2 2 2 2 2 5 2 2 1 1 4 2 2 2 2 4 3 2 2 2 2 3 2 1 1 1 1 4 2
Cynanchum acutum 2 2 2 2 2 2 4 4 2 1 1 5 2 2 2 2 5 4 4 2 2 2 2 1 2 3 2 1 1 1
Solenostemma argel 2 4 1 3 2 2 4 1 2 1 1 1e 2 1 1 2 5 5 5 2 2 2 1 2 1 3 2 2 2 1
Asclepias curassavica 1 2 2 1 2 2 4 4 2 1 1 6 2 2 2 2 2 - - - - - - 1 2 2 1 2 5 2
Cryptostegia grandiflora 2 2 2 1 2 2 4 4 2 1 1 7 2 2 2 2 5 - - - - - - 1 2 1 2 1 2 1
Inapplicable character-s
ГО OJ OJ
Plate 1 Seed morphology of 14 species of Apocynaceae (1-7) and Asclepiadaceae (8-14) as revealed by light microscopy: 1. Acokanthera spectabilis; 2. Carissa spinarum; 3. Thevetiaperuviana; 4. Catharanthus roseus; 5. Alstonia scholaris; 6. Nerium oleander; 7. Mascarenhasia elastica; 8. Leptadenia arborea; 9. Leptadenia pyrotechnica; 10. Calotropis procera; 11. Cynanchum acutum; 12. Solenostemma argel; 13. Asclepias curassavica; 14. Cryptostegia grandiflora.
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гаки bisse 50um4 eal^H^^B
•л ,,
.....tf ¿PG
? Ц* ^ P
2J0Î Lp . X3,30j 0
Plate 2 Surface sculpture of seeds of 14 species of Apocynaceae (1-7) and Asclepiadaceae (8-14) as revealed by SEM. 1. Acokanthera spectabilis; 2. Carissa spinarum; 3. Thevetiaperuviana; 4. Catharanthus roseus; 5. Alstonia scholaris; 6. Nerium oleander; 7. Mascarenhasia elastica; 8. Leptadenia arborea; 9. Leptadenia pyrotechnica.
n.' 'ßi h / ' 'V, y
\ V * Vx
, X 7 y ' 1 1 r * / V / . S
A w V * '¡)<¿r m
Fig. 2 (continued): Surface sculpture of seeds of 14 species of Apocynaceae (1-7) and Asclepiadaceae (8-14) as revealed by SEM. 10. Calotropis procera; 11. Cynanchum acutum; 12. Solenostemma argel; 13. Asclepias curassavica; 14. Cryptostegia grandiflora.
Plate 3 Photomicrographs of cross-sections of seed coat of 14 species of Apocynaceae (1-7) and Asclepiadaceae (8-14). 1. Acokanthera spectabilis; 2. Carissa spinarum; 3. Thevetiaperuviana; 4. Catharanthus roseus; 5. Alstonia scholaris; 6. Nerium oleander; 7. Mascarenhasia elastica; 8. Leptadenia arborea; 9. Leptadenia pyrotechnica; 10. Calotropis procera; 11. Cynanchum acutum; 12. Solenostemma argel; 13. Asclepias curassavica; 14. Cryptostegia grandiflora.
Acknowledgment
I thank Prof. Azza A. Khafagi and Prof. Amaal H. Mohamed
(Faculty of Science for girls, Al-Azhar University) for invaluable comments.
References
Abdel Khalik, K., 2013. Systematic implications of seed coat diversity in some representatives of the genus Ipomoea (Convolvulaceae). Turk. J. Bot. 37, 811-824.
Abdel Khalik, K., Vander Maesen, L.J.G., 2002. Seed morphology of some tribes of Brassicaceae (implications for taxonomy and species identification for the flora of Egypt). Blumea 47 (2), 363-383.
Al Nawaihi, A.S., Hassan, S.A., Elwan, Z.A., 2006. Exomorphic seed characters of species of Apocynaceae in Egypt. Feddes Repert., Weinheim 117, 437-452.
Al-Gohary, I., Mohamed, A.H., 2007. Seed morphology of Acacia in Egypt and its taxonomic significance. Int. J. Agric. Biol. 9 (3), 435438.
Bailey, L.H., 1916. Standard cyclopedia of horticulture, vol. 4. The Macimillan company, London.
Barthlott, W., 1981. Epidermal and seed surface characters of plants: systematic applicability and some evolutionary aspects. Nord. J. Bot. 1, 345-355.
Barthlott, W., 1990. Scanning electron microscopy of the epidermal surface in plants. In: Claugher, D. (Ed.), Scanning Electron Microscopy in Taxonomy and Functional Morphology. Clarendon, Oxford, pp. 69-94.
Boulos, L., 2000. Flora of Egypt, vol. 2. Al Hadara Publishing Cairo, Egypt, pp. 210-229.
Brisson, J.D., Peterson, R.L., 1976. A critical review of the use of scanning electron microscopy in the study of the seed coat. In: Proceedings of the Workshop on Plant Science Applications of the SEM-IIT Research Inst. Chicago, vol. 7(2), pp. 477-495.
Brisson, J.D., Peterson, R.L., 1977. The scanning electron microscope and X-ray microanalysis in the study of seeds: a bibliography covering the period of 1967-1976. In: Scanning Electron Micros-copy-IIT Research Inst. Chicago, vol. 2, pp. 697-712.
Cole, G.T., Behnke, H.D., 1975. Electron microscopy and plant systematics. Taxon 24, 3-15.
Dahlgren, R. 1980. Angiospermernes taxonomi 1-3. Copenhagen.
Davis, P.H., 1975. Flora of Turkey. Edinburgh, 158-174.
Dilcher, D.L., 1974. Approaches to the identification of Angiosperm leaf remains. Bot. Rev. 40 (1), 86-116.
Dlcdm, A., Ozay, S.G., KOkddl, G., 2010. Exomorphic seed characters and anatomy of leaf and stem of some Vincetoxicum (Asclepiadaceae/Apocynaceae) species from Turkey. Ankara Ecz. Fak. Derg. J. Fac. Pharm, Ankara 39 (1), 1-16.
Endress, M.E., Bruyns, P.V., 2000. A revised classification of Apocynaceae s.l. Bot. Rev. 66, 1-56.
Heywood, V.H., 1971. Scanning electron microscopy. Systematic and evolutionary applications.
Hutchinson, J., Dalziel, J.M., 1963. Flora of west tropical Africa. vol. 2, London, 51-103.
Juan, R., Pastor, J., Fernandez, I., 2000. SEM and light microscope observations on fruit and seeds in Scrophulariaceae from southwest Spain and their systematic significance. Ann. Bot. 86, 323-338.
Kanak Sahai, Harbans, K., Aruna, P., 1997. Macro- and micromor-phological seed characteristicsof some Cassia species and their taxonomic significance. Phytomorphology 47, 273-279.
Karam, M.F., 1997. Scanning Electron Microscope studies of seed characters in Trifolium L. (Fabaceae). Phytomorphology 47, 51-56.
Koul, K.K., Ranjna, N., Raina, S.N., 2000. Seed coat microsculptur-ing in Brassica and allied genera (subtribes Brassicinae, Raphani-nae, Moricandiinae). Ann. Bot. 86, 385-397.
Kumar, C.A., Bindu, S., Chitra, C.R., Mathew, P.J., 2011. Taxonomic significance of fruit and seed morphology in identification of South Indian Rauvolfia (Apocynaceae). Rheedea 21 (2), 160-166.
Leeuwenberg, A.J.M., 1994. Taxa of the Apocynaceae above the genus level. Series of revisions of Apocynaceae, XXXVIII. Wageningen Agric. Univ. Pap., vol. 94(3), pp. 45-60.
Lindley, J., 1932. Flora medica; A botanical account of all the more important plants used in medicine. Longman, London, pp. 527545.
Metcalfe, C.R., Chalk, L., 1979. Anatomy of the dicotyledons (1), vol. 55. Clarenedon Press, Oxford.
Omlor, R., 1998. Generische revision der Marsdeniea (Asclepiadaceae) Aachen: Shaker verlag. Ph.D. diss., Universität Kaiserslautern.
Pandey, B.P., 1997. A text book of botany Angiosperms. S. Chand and Company LTD, Ramnagar, New Delhi.
Pichon, M., 1948. Classification des Apocynacees. I. Carissees et Ambelaniees. Mem. Mus. Natl. Hist. Nat., Ser. B, Bot. 24, 111181.
Pichon, M., 1949. Classification des Apocynacees. IX. Rauvolfiees, Alstoniees, Allamandees et. Taberna^montanoid^es. Mem. Mus. Natl. Hist. Nat. 24, 153-251.
Segarra, J.G., Mateu, I., 2001. Seed morphology of Linaria species from eastern Spain: identification of species and taxonomic implications. Bot. J. Linn. Soc. 135, 375-389.
Stearn, W.T., 1992. Botanical Latin. David and Charles Publication, London.
Tackholm, V., 1974. Students' flora of Egypt, second ed. Cairo Univ. Publication, Corporative Printing Co., Beirut.
Vaughan, J.G., 1968. Seed anatomy and taxonomy. Proc. Linn. Soc. Lond. 79, 251-255.
Zainhasan, S.M., Lester, R., 1990. Comparative micromorphology of the seed surface of Solarium melongena L. (eggplant) and allied species. Pertanika 13 (1), 1-8.
