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Seedling characters for correlation of some species of CohortUnisexuales (sensu Bentham and Hooker) in the Forest Patches

of Dakshindinajpur, West Bengal

P. Kamilya and Ayan DasDepartment of Botany, Balurghat College, Balurghat 733101, Dakshindinajpur, West Bengal, India

E-mail: [email protected] & [email protected]

[Received 31.10.2014; Revised 19.12.2014; Accepted 24.12.2014; Published 31.12.2014]

AbstractSeedling morphology of twenty-four taxa of the families (= natural orders) Euphorbiaceae andUrticaceae of the order (= cohort) Unisexuales (sensu Bentham & Hooker 1862 – 1883) havebeen studied from different forest patches of Dakshindinajpur District of West Bengal. Theseseedlings are described on the basic parameters for characterization of seedlings. Correlation ofthe taxa has been shown using seedling characters with UPGMA method to understand whetherthis correlation has any connection with natural system of classification.

Key words: Seedlings, Seedling characters, Correlation, Dendrogram

INTRODUCTION

Seedling development is an early juvenile stage in plant’s life cycle. Non-volatile morphologicalcharacters of seedlings are very important to understand this initial process of plant life cycle(Paria et al 2006). Different taxa within the same or different groups exhibit diversity in thisstage and on the basis of which correlation can be drawn to understand the variability in thenatural characters among them. Many workers like Naidu & Shah 1978; Sampathkumar1982; Balasubhramanyam & Swarupanandan 1986; Deb & Paria 1986; Kamilya & Paria1993a,b, 1997; Paria & Kamilya 1999; Paria et al. 1990, 2006; Kamilya 2011; Duke 1965,1969; De Vogel 1980; Bokdam 1977; Ng 1975; Popma & Bongers 1988; Guillermo et al.2001 and Zanne et al. 2005 have worked to understand the impact of seedling characters ontaxonomy. However, correlation among taxa on the basis of seedling morphology is rare intheir works. In this work, an attempt has been made to understand the numerical relationshipamong taxa depending on seedling characters of twenty–four species of which sixteen ofthe family Euphorbiaceae and eight of the family Urticaceae under the order Unisexuales(sensu Bentham & Hooker 1862–1883). Numerical analysis has been carried out on thebasis of their seedling characters to draw correlation among them. In addition, we tried tofind out whether this correlation matches traditional system or not.

MATERIALS AND METHODS

The study was conducted in different natural and seminatural forest patches of Dakshindinajpurdistrict of West Bengal during August, 2013 to September, 2014. The total forest area in thedistrict is 2.95 sq km (Mitra & Mukherjee 2013) with mean annual rainfall 1847.8 mm andmean annual temperature varying from 23 – 29º C. The vegetation is mostly semi-deciduoustype (Kamilya 2011).

Pleione 8(2): 416 - 426. 2014. ISSN: 0973-9467© East Himalayan Society for Spermatophyte Taxonomy

Seeds and seedlings are collected from their natural habitat in different forests atdifferent times. The seeds are sown in garden of the Department of Botany, BalurghatCollege and seedlings were raised. The natural seedlings are then compared with the raisedones for identification. Herbarium sheets are made with the pressed and dried seedlings anddiagnosed following Duke 1965; Burger 1972; DeVogel 1980 and Paria et al. 2006. Seedlingsare then characterized and an artificial key to the taxa has been made for the identificationof seedlings in natural habitat.

For statistical analysis, characters were considered in numerical form as shown inTable–I. To understand the interrelationships among the taxa, a dendrogram has been createdusing DendroUPGMA software. DendroUPGMA makes clustering from a set of variablesfrom similarity or dissimilarity matrix using Unweighted Pair Group method with ArithmeticMean (UPGMA) algorithm (Garcia-Vallve 1999). The numerical characters are put in fasta–like format and the system is run in Pearson coefficient to measure linear correlation betweenthe OTUs (Sneath & Sokal 1973). The outcome is in phylip format where mean branchdivergence value between the taxa is displayed from which finally produce the dendrogram.

The seedlings are displayed in the form of field photographs with highlightedparacotyledons and first two leaves for some of the studied species [PLATE - I] and handdrawings for others [PLATE - II]. Their characters are shown in the form of numericals(Table I) with the related characters for each value below the table. The taxa are arrangedalphabetically in the table along with references to figure and voucher numbers. Thoughseedlings are described upto 7th to 10th leaves stage, but due to more prominent distinctivenature it was considered up to 1st two leaved stage only.

RESULT

The observations on the structure of seedlings and the result of the numerical survey hasbeen presented in Table 1. PLATES I & II presented the photographs and drawings of theseedlings under study.

Based on the morphological characters a Key has been prepared to identify these seedlingsin natural conditions:

Artificial Key to the seedling species (Key valid for taxa studied only):

1. Seedlings phanerocotylar …………… …………… ...........…… 21a. Seedlings cryptocotylar …………… …………… .............…… 222. Apex of paracotyledons other than retuse …………… …………... ........ 32a. Apex of paracotyledons retuse …………… …………… .....…… 193. Hypocotyl strictly rounded; first 2 leaves always opposite ………........ .......... 43a. Hypocotyl may be rounded or angular; first 2 leaves opposite or alternate …....… 124. Apex of paracotyledons obtuse or shallowly sinuate, primary vein 1, 3 or 7; first 2

leaves, elliptic, widely elliptic or obovate, base cuneate or rounded, venationcamptodromous ...................... .................... ................... .......…. 5

4a. Apex of paracotyledons rounded or truncate, primary veins 5; first 2 leaves orbicularor ovate, base peltate, cordate or truncate, venation actinodromous …………… 9

5. Paracotyledons elliptic, oblong or flabellate; tip of first 2 leaves obtuse or mucronate .. 65a. Paracotyledons ovate; apex of first 2 leaves acute ………… Glochidion ellipticum

P. Kamilya & Ayan Das 417

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418 Seedling characters of some species of Cohort Unisexuales

6. Hypocotyl pubescent; number of primary veins in paracotyledons 3 or 7, venationactinodromous; first 2 leaves elliptic or widely elliptic, obtuse ….………... .... 7

6a. Hypocotyl glabrous; number of primary veins in paracotyledons one, venationhyphodromous; first 2 leaves obovate, mucronate ………………… Breynia retusa

7. Paracotyledons oblong or flabellate, apex shallowly sinuate; first 2 leaves widely elliptic;first internode pubescent or tomentose …………… ................... ..... 8

7a. Paracotyledons elliptic, obtuse; first 2 leaves elliptic; first internode glabrous ............ ………… Antidesma acidum

8. Paracotyledons oblong, slightly oblique, primary veins 5; base of first 2 leaves cuneate;first internode pubescent ………… ................. .... Bridelia stipularis

8a. Paracotyledons flabellate, not oblique, primary veins 7; base of first 2 leaves rounded;first internode tomentose …………… ................... Bridelia tomentosa

9. Hypocotyl glabrous; paracotyledons oblong, base rounded, apex rounded; base of first 2leaves peltate or cordate, apex rounded or acute, glandular hair present on the petiole;heteroblastic development present ………….... ................ ........ 10

9a. Hypocotyl pubescent or sparsely pubescent; paracotyledons obovate, truncate, basecuneate; base of first 2 leaves truncate, apex acuminate, glandular hair not present;heteroblastic development absent …………... ..................... ........... 11

10. First 2 leaves orbicular, base peltate, apex rounded …….....… Jatropha podagrica10a. First 2 leaves ovate, base cordate, apex acute ………… Jatropha gossypifolia11. Hypocotyl sparsely pubescent; margin of first 2 leaves dentate; first internode round,

tomentose …………... ................. ................... Mallotus repandus11a. Hypocotyl densely pubescent; margin of first 2 leaves serrate; first internode angular,

hirsute …………..... ........................ ....... Mallotus philippinensis12. Apex of first 2 leaves acute, obtuse or acuminate, venation actinodromous or

camptodromous …………... …………... …………... ......……… 1312a. Apex of first 2 leaves always acute, venation always camptodromous …….…… 1713. Petioles of paracotyledons adaxially deeply concave, paracotyledons suborbicular or

flabellate, apex shallowly sinuate or rounded, venation actinodromous; base of first 2leaves cuneate, attenuate, cordate or truncate, margin dentate or crenate dentate

…………… 1413a. Petioles of paracotyledons dorsiventrally flattened dorsally shallowly channeled,

paracotyledons oblong, apex obtuse, venation hyphomous; base of first 2 leavesrounded, margin serrate ..…........... …………... ............... Trema orientalis

14. Apex of paracotyledons shallowly sinuate; first 2 leaves elliptic, venationcamptodromous; first internode glabrous …………... ……...…… ....... 15

14a. Apex of paracotyledons rounded; first 2 leaves ovate, venation actinodromous; firstinternode pubescent …………… …………... …………... ........... 16

15. Paracotyledons flabellate; base of first 2 leaves cuneate, apex obtuse, margin dentate;first internode angular …………… …………... ........ Aporusa octandra

15a. Paracotyledons suborbicular; base of first 2 leaves attenuate, apex acute, margincrenate dentate; first internode round ………… …………. Suregada multiflora

16. Hypocotyl angular, pubescent; primary veins in paracotyledons three; first 2 leavesexstipulate, base cordate, apex acute; first internode angular......Macaranga denticulata


16a. Hypocotyl round, glabrous; primary veins in paracotyledons five; first 2 leavesstipulate, base truncate, apex acuminate; first internode round .......Trewia nudiflora

17. Hypocotyl with pubescent or hirsute hair; paracotyledons ovate or obovate; basecordate or auriculate; base of first 2 leaves cuneate or rounded, margin serrate .… 18

17a. Hypocotyl with stellate hair; paracotyledons oblong; base rounded; base of first 2leaves truncate, margin dentate …………… …………... Croton roxburghii

18. Hypocotyl pubescent; paracotyledons ovate, base cordate, apex obtuse; first 2 leavesalternate, elliptic, base cuneate; first ineternode round, pubescent .. Drypetes roxburghii

18a. Hypocotyl hirsute; paracotyledons obovate, base auriculate, apex rounded; first 2leaves opposite, ovate, base rounded; first ineternode angular, hirsute ..................................................... ........................ .............. Tragia involucrata

19. Primary veins in paracotyledons one, venation camptodromous or hyphodromous;margin of first 2 leaves serrate or dentate ………....... ………... ...... 20

19a. Primary veins in paracotyledons two, venation actinodromous; margin of first 2leaves entire ………....... …………... …………... Ficus benghalensis

20. Paracotyledons obovate, venation hyphodromous; first 2 leaves alternate elliptic, basecuneate, apex acute, margin serrate; first internode glabrous or hispid …………… 21

20a. Paracotyledons ovate, venation camptodromous; first 2 leaves opposite, baserounded, apex obtuse, margin dentate; first internode pubescent ….. Ficus religiosa

21. First 2 leaves and internode glabrous ……......... ………... Ficus racemosa21a. First 2 leaves and internode tomentose ……......... ……….... Ficus hispida22. Cataphylls present, base rounded, apex acute …………..... …………... 2322a. Cataphylls absent, base attenuate, apex obtuse …………... .... Streblus asper23. Shape of first 2 leaves ovate, margin entire, surface of first internode pubescent .....

………....... …………... …………... ...... Artocarpus heterophyllus23a. Shape of first 2 leaves widely elliptic, margin serrate, surface of first internode

hirsute …..……...... …………... …………... .... Artocarpus lacucha

DISCUSSION

In the prepared dendrogram (Figure 1), two principal clusterings are displayed– one withthe twenty–one taxa showing phanerocotylar mode of germination and the rest three taxawith cryptocotylar mode of germination having mean branch divergence value or mbdv40.934. The clustering of phanerocotylar genera is divided into two clades with mbdv38.833 having seventeen species in one assemblage and four members in the other. Theseventeen taxa are further segregated at mbdv 32.391 into two secondary clades withnine and eight taxa respectively. Each of these two secondary clades then forms twoclusterings i.e, clusterings ‘a’ and ‘b’ for the first one and clusterings ‘c’ and ‘d’ for thesecond one.

Clustering ‘a’ consists of five taxa, where Glochidion ellipticum segregates fromothers at mbdv 18.829. Next, Breynia retusa and Antidesma acidum with Bridelia spp.are separated respectively at mbdv 14.719. The two species of Bridelia remain undersame clade with mbdv 4.275 due to differences in their base of first two leaves and haircharacters of first internode as mentioned in the artificial key. Four taxa of ‘b’ clusteringshow two groups at mbdv 23.039 containing one genus and two species in each. In one


PLATE - I: 1. Antidesma acidum; 2. Aporusa octandra; 3. Bridelia tomentosa; 4. Artocarpusheterophyllus; 5. Artocarpus lacucha; 6. Drypetes roxburghii; 7. Ficus benghalensis; 8. Ficusracemosa; 9. Ficus hispida; 10. Ficus religiosa; 11. Jatropha podagrica; 12. Jatropha gossypifolia;13. Mallotus philippinensis; 14. Mallotus repandus; 15. Streblus asper; 16. Suregada multiflora;17. Tragia involucrata; 18. Trema orientalis; 19. Trewia nudiflora


PLATE - II: 1. Bridelia stipularis; 2. Breynia retusa; 3. Glochidion ellipticum; I4. Macarangadenticulata; 5. Croton roxburghii

Figure 1. Dendrogram showing clusters of 24 taxa


group, Jatropha gossypifolia and J. podagrica are placed at mbdv 13.871 with thedifferences of shape, base and apex of first two leaves as depicted in the artificial key. Inthe other group, Mallotus repandus and M. philippinensis are very much closer havingthe mbdv of 3.302.

Clustering ‘c’ has five species, among which Trema orientalis forms a single cladefrom the rest by mbdv 23.482. The other four species are separated into two subclades withtwo members of each. The first subclad consists of Aporusa octandra and Suregadamultiflora which are displayed at mbdv 3.535. Trewia nudiflora and Macaranga denticulataform the second subclade with mbdv 7.676. Clustering ‘d’ displays three taxa where Drypetesroxburghii and Tragia involucrata show closer proximity (mbdv 16.203) in one clade whileCroton roxburghii makes another clade differing from the former at mbdv 23.648.

The other primary clade with phanerocotylar taxa having mbdv 38.833 has four speciesof Ficus. Among these, F. racemosa and F. hispida remain in closer proximity with mbdv5.170 as they are distinguished only on the hair characters of first internode. F. religiosadisplays the next proximity with them with mbdv 26.039. F. benghalensis forms anotherdistant clade within this group with mbdv 29.947 with references to the characters shown inthe artificial key.

The cryptocotylar clustering is made by three taxa, two species of the genus Artocarpusand one species of Streblus. S. asper forms a single clade at mbdv 18.613 apart from therest two of this group. The two species of Artocarpus, viz., A. heterophyllus and A. lacuchadepict mbdv 14.099 and represent a same clade only having only distinction of the characterslike shape and margin of first two leaves as in the key.

CONCLUSION

The order (Cohort) Unisexuales sensu Bentham and Hooker comprises of nine naturalorders (= families), of which we have studied the seedling morphology of sixteen membersof Euphorbiaceae and eight members of Urticaceae only. The recent classification systemshave further splitted the above two families [e.g. Takhtajan 1997; Chase & Reveal 2009(APG– III)]. Within this limited number of studied taxa, the phanerocotylar taxa, Ficusspp. of Urticaceae make separate clade being placed at mbdv 38.833 while Trema orientalisof the same family is placed within the clustering clade ‘c’ of Euphorbiaceae indicating itsanomalous position. Besides cryptocotylar clade having taxa Artocarpus heterophyllus,A. lacucha and Streblus asper remaining seventeen taxa within the clusterings ‘a’, ‘b’,‘c’ and ‘d’ displayed a single clustering after being separated from Ficus spp. Differentsubclades or secondary clades within the ‘a’, ‘b’, ‘c’ and ‘d’ are not parallel with therecent classification system of Euphorbiaceae. Therefore, seedling characters arestrengthening the separation of these taxa within Euphorbiaceae and Urticaceae underUnisexuales. However, strict adherence is possible if large number of species are studiedin such field.

Some parallel behaviour of seedling subclades to other botanical disciplines has alsobeen made. From view point of palynological evidence, Glochidion ellipticum and Breyniaretusa show similarity in pollen characters (Pax & Hoffmann 1922), which is almost similarto seedling characters being placed in clustering ‘a’ of dendrogram. Similarly Glochidionellipticum and Aporusa octandra are anatomically far apart from each other (Metcalfe &Chalk 1950) supporting the subclade of seedling.

Thus, correlation of seedling data can partially fulfil natural clustering as well as moderntaxonomy.


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Acknowledgement

The authors are grateful to UGC for providing financial help in the form of Major ResearchProject [F. No. 41-484/2012(SR) dt. 16.07.2012].


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