Scholarly article on topic 'Seed morphology and seed coat anatomy of some species of Apocynaceae and Asclepiadaceae'

Seed morphology and seed coat anatomy of some species of Apocynaceae and Asclepiadaceae Academic research paper on "Biological sciences"

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Abstract of research paper on Biological sciences, author of scientific article — Dalia G. Gabr

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 taxonomic value of the recorded characters is indicated by the richness of variation recorded in the limited sample of genera and species.

Academic research paper on topic "Seed morphology and seed coat anatomy of some species of Apocynaceae and Asclepiadaceae"

Annals 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.

© 2014 Production and hosting by Elsevier B.V. on behalf of Faculty of Agriculture, Ain Shams University. Open access under CC BY-NC-ND license.

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).

http://dx.doi.org/10.1016/j.aoas.2014.11.010

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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.

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