Perspective of Plant Biodiversity 483-498, 2002 Edited by A.P. Das Pubtished by Bishen Singh Mahendra Pal Singh MORPTIOLOGICAL DTV-ERSITIES AND TAXONOMIC SIGNIFTCANCE OF CYPSELARFEATURES IN THE GENUS Aster L. (ASTBREAE - ASTERACEAE) Nandita Basak and Sobhan Kr. Mukherjee Departntent of Botany, University of Kalyani, Kalyani-V4l 235, India ABSTRACT Exomorphic features of cypselas in Asler ageratoides subsp. alatopetiolata, A. tlaccidus ssp.tlaccidus, A. f accidus ssp. glandulosus, A. himalaicus, A. sikkimensis, A. stracheyi and A. trinervius var. trinervirrs of the tribe Astereae of the family Asteraceae have been investigated. Typical rwin hairs are found in all nine species of Aster but multicellular glandular hairs exist in six spccics. Pappus bristles are usually thick, homomorphic, scabrous bristles type which are found in seven species while the other two species including two subspecies of one species have distinctly dimorphic pappus bristles. Shape of cypsela often varies from narrowly oblong" to oblanceolate, seldom elliptic to obovate in A. alpinus. Thickness of carpopodial cells and number of ribs are diacritical for species identity. Plane of the distal end of twin hair is also valuable. Colour of cypsela and structure of stylopodium are not significant taxonomically. Though the morphological features of cypselas of Aster is greatly variable in different species, there are some common features like (i) presence of dorsiventrally compressed cypsela with 2-5 ribs, (ii) cypsela with asymmetric, complete carpopodial ring, (iii) presence of scabrous pappus bristles arranged in l-2 rows, (iv) presence of twin hairs throughout the surface cxcept in carpopodial region. So, these variable exomorphic features of cypselas may be employed for characterization of taxa. albescens, A. alpinus, A. asteroides, A. INTRODUCTION Aster L., a cosmopolitan genus, with about250 species, belonging to the subtribe Asterinae under the tribe Astereae (Asteraceae) is mainly distributed in the northern hemisphere. (Grau , 1977).It has 33 species in Himalayan region (Mabberly,1997) and about 23 species in Indian region (Hajra et al., 1995). Bremer ( 1987) has mentioned that the tribe Astereae is distinguished from rest of Asteraceae by the absence of pentaynene and sesquiterpene lactones. . t 484 on the different parts of cypselas As very little information is available 1984; Mukherjee' in Aster(Grau, 1977;Velez' 1981; Haque & Codward' has been taken up to describe l99l; Nesom, lg94),the present investilation urr.r, the value of this information the structural details of cypselas ,o account deals with the structure of for toxonomic purposes. The present oi of the genus Aster L. including 2 subspecies cypselas in nine one species. ,i."i., MATERIALS AND METHODS collected by the second The cypselas of nine species of Aster were and one species (A' alpinus L') author from Sikkim Himalayan region Contt*atoire et Jardin Botaniques was obtained from the Herbarium of Geneve,Geneva.Drycypselasweresoftenedbyboilingwithwaterwith minutes. Entire cypselas and different a few drops of glycerol for about 5 partsofcypselu,*.,.stainedin0.5%aqueoussafraninsolutionand the middle section of cypselas at mounted inlIYoglycerine solution. cross were made under part were tak;. Drawings and observations microscopes with the.help of stereodissecting binocular und "o.pound voucher specimens are preserved in the mirror type ca'mera lucida" of Kalyani' The morphology Herbarium, Botany Department, University as proposed by of cypselas were O.r.iiU.a following the terminology Kynclova(1970)Grau(|gll)andMukherjee(1991).Thenamesofthe investigated specie s of Aster is given below: l.Aslerageratoidesturcz.subsp.alatopetiolataKitam. 2. A. albescens (DC') Hand-Marz' 3. A. alPinus L. 4. A. asteroides (DC') O' Kuntz 5. A. flaccidus Bunge subsp' tlaccidus 6. A. /laccidus Bunge subsp' glandulosus (Keissl') Onno 7. A. himalaicus C' B' Clarke 8. A. sikkimensis Hook' f' g. A, stracheYi Hook' f' lO. A. trinervius Roxb' ex D' Don var' lrinervius 485 RESULTS Morphotogical Descriptions of Cypselas l. Aster ageratoides irrrcz. subsp. alatopetiolata Kitam (Fig l, A-J) Cypsela homomorphic, narrow obovate to oblanceolate, 1.25'1.3 n'rnr x 0.25-0.3 mm, blackish brown, straight, gradually narrowed towards base, considerably compressed anterio-posteriorly with trvo lateral protninent ribs. Cypsela surface densely covered by acroscopic 'twin' hairs with distinctly unequal tips and few biseriate capitate glandular hairs. Glandular hairs usually found at the apical and middle parts of cypselas. Stylopodium not very prominent. Carpopodium asymmetric, narrow, complete ring (fronr top view) or cup like (from lateral view), brownish, diameter nearly samc as base of cypsela. Carpopodial cells quite distinct morphologically from the cells of the cypselar wall; vertically arranged in 2-4 horizontal rows, thick-walled. Pappus bristles uniseriate, persistent,3-3.5 mm long, brownish, thin, scabrous, numerous, more or less free. 2. Aster albescens (DC.) Hand-Mazz. (Fig l, K-T) Cypsela homomorphic, more or less oblong, 1.2-5-1.4 mm,x 0.25-0.3 mm, blackish brown, straight, slightly nanowed towards base, considerab!1, compressed anterio-posteriorly with two lateral prorninent ribs and two less prominent ribs at anterior and posterior sides. Cypsela surface densely covered by acroscopic 'twin' hairs with more or less equal tips and few biseriate capitate glandular hairs usually found at apical part of cypselas. Stylopodium very short and not so prominent. Carpopodium asymmetric, narrow, complete ring (from tip view) or cup like (from lateral view), brownish, diameter nearly silne as base of cypsela. Carpopodial cells quite distinct morphologically from the cells of the cypselar wall; horizontally arranged in 5-7 horizontal rows, thick-walled. Pappus bristles uniseriate, persistent,4-4.5 mm long, brownish, thin, scabrous, numerous, more or less free. 3. Aster alpitrus L. (Fig 2, A-I) Cypsela nomomorphic, wide obovate, 3.25-3.35 mm r 1.7.1.8 mm, blackish brown, straight, narrowed at both ends but more towar.ds the base, considerably compressed anterio-posteriorly with two lateral prominent ribs. Cypsela surface densely covered by acroscopic 'twin' hairs with more or 486 i.k iili ;t {w lg F EI stl OL ,I rl { rl II *l oL o Flg. l. A-1. Aster ageratoides subsp. alatopetiolara A. Cypscla, B. Apicalpart of cypseta, Basal part of cypsela, D. cypselar suiface, E. Glandular hair, F. Twin hair, G. Carpopodial cells, H. Basal part of pappus bristle. t. Middle part of pappus bristle, J. Apical part of pappus bristle. K-T. l. albescens K. cypsela, L. Apical part of cypsela, M. Basal part of cypscla, N. cypsclar surfacc, o. Glandurar hair, p. Twin hair, e. carpopodial cells, R. Basal part of pappus bristle, S. Middle part of pappus bristlc. T. Apical part of pappus bristle. c. 487 l )t l € :{ o Ii ;l :I iL Fig. 2. Aster alpinus. A. cypsela, B. Apical part of clpsela, c. Basal part of cypsela, part D.-Cypsetar surface, E. Glandular hair, F. Twin hair, G. Carpopodial cells, H' Basal bristlc' of puppus bristle. I. Middle part of Pappus bristle, J. Apioal part of PaPpus less equal tips and fcw biseriate capitate glandular hairs. Glandular hairs usualli found at apical and middle parts of cypselas. Stylopodium vcry -arpopodium asymmetric, natrow' complete ring (from short, tylindrical. top vicw) or strap like(fiom lateral view), whitish brown, diameter nearly same as base of cypsela. Carpopodial cells quite distinct morphologically from the cells of tire cypselar wall; vertically arranged in 2'4 horizontal rows, thick-walled. Pappus bristles uniseriate' persistent, 4'6 mm long, brownish, thin, scabrous, numerous' more or less free' 4. Aster asteroides (DC.) O. Kuntze (Fig 3' A-K) cypsela homomorphic, obovate to oblanceolate, 1.25-l .4 mm x 0'70.8 mm, brown, straigirt, nalrowed at both ends but more towards base, ribs at anterior considerably comprest.d *t.tio-posteriorly with two oblique .188 E f "{ 5 € -El 6L Flg. 3. Aster asleroides. A. Cypsela, B. Apical part of cypsela, C. Basal part of cypsela, D. Cypselar surface, E. Twin hair, F" Carpopodial cells. G. Apical part of outer scale, H. Basal part of outer scale, I" Basal pa( of inner pappus bristle, J. Middle part of inner pappus bristle, K. Apical part of inner pappus bristle. 'twin' short and posterior sides. Cypsela surface densely covered by acroscopic hairs with ne.arly equal tips. Glandular hairs absent. Stylopodium very and not so prominent. Carpopodium asymmetric, wide, complete ring (from top view) or elliptic strap like (from lateral view), brownish white, diamcter nearly same as base of cypsela. Carpopodial cells quite distinct morphologically from the cells of cypselar wall; horizontally oriented in 23 horizontal rows, thick-wallcd" Pappus bristles dimorphic, biseriate; outer : i . : ' 489 J scales shorter than inner bristles, persistant, thick, many, free, about 0.7 mm long and inner bristles about 2.5-3 mm long, scabrous, persistent, brownish. 5. Asterfiaccidus Bunge subsp. fiaccidus (Fig. 4, A-K) Cypsela homomorphic, oblong to oblanceolate, 1.8-1.9 mm x 0.2-0.4 IrIm, brovnish, straight, gradually narrowed towards the base, considcrably compressed anteno-posteriorly with two lateral prominent ribs. Cypscla surface densely covered by acroscopic 'twin' hairs with nearly equal tips. Glandular hairs absent. Stylopodium short, not so prominent. Carpopodium asymmetric, wide, complete ring (from top view) or strap like (fronr lateral view), brownish, diameter nearly same as the base of the cypscla. Carpopodial cells quite distinct morphologically from the cells of thc cypselar wall; vertically and horizontally oriented in 3-4 rows, thick-walled. Pappus bristles biseriate, distinctly dimorphic; outer scales shorter than inner bristles, persistent, thick, many, free, 0.4-0.5 nrm long and inner bristles about 4 mm long, scabrous, persistent, yellowish. 6, Aster flaccidus Bunge subsp. glandulosas (Keissl.) Onno (Fig. 5. A-L.) Cypsela homomorphic, oblong to oblanceolate, 1.9-2 mm x 0.5-0.55 mm, blackish brown, straight, slightly narrow at the base, slightly compressed anterio-posterior by two prominent lateral and two less prominent ribs at anterior and posterior sides. Cypsela surface denscly covered with acroscopic 'twin' hairs with slightly unequal tips and few biseriate capitate glandular hairs. Glandular hairs usually found at the apical part of the cypsela. Stylopodium very short, not so prominent. Carpopodium asymmetric, wide, complete ring (from top view) or strap like (from later view), brownish, diameter nearly same as base of cypsela. Carpopodial cells quite distinct morphologically from the cells of clpselar wall; vertically oriented in 4-5 horizontal rows, thick-walled. Pappus bristles dimorphic, biseriate; outer scales shorter than inner bristles, persistent, thick, many, more or less free, 0.6-0.7 mm long and inner bristles about 4 mm long, scabrous, persistent, brownish. 7. Aster himalaicus C.B. Clarke (Fig. 6, A-I) x 0.25-0.3 mm, blackish brown, straight, slightly narrowed towards base, slightly Cypsela homomorphic, nearly oblong, 0.8-0.9 mm 490 compressed anterio-posteriorly, with 4 prominent ribs. Cypsela surface densely covered by acroscopic 'twin' hairs. Glandular hairs absent. Stylopodium absent. Carpopodium asyrnrnetric, narrow, complete ring (from top view) or strap like (from lateral view), white, diamcter nearly same as base of cypsela. Carpopodial cells quite distinct morphologically from cells of cypselar wall; vertically and horizontally oriented in2-3 rows, thick- 5,. :{/ ol Flg. 4.'Aster fl accrdns subsp./a ccidus. A. Cypsela, B. Apical part of cypsela, C. Basal part of cypsela, D. Cypselar surface, E. Twin hair, F. Carpopodial cells, C. Apical part of outer scale, H. Basal part of outer scale, I. Basal part of inner pappus bristle, J. Middle part of inner pappus bristlc, K. Apical part of inner pappus bristle. 491 j Fig. 5. Aster laccidus subsp. glandulosus. A. Cypsela, B. Apical part of cypsela, C' Bial part oi cypsela, o. sur-r".e of cypsela, E. Glandular hair, F. Twin hair, G. Carpopodial celis, H. Apical part of outei scate, I. Basal part of outer scale, J' Basal puri oi inner pappus bristle, ti. UiOOl" part of inner pappus bristle, L. Apical part of inner pappus bristle. 492 5-5.5 mm long, yellowish, thin, walled. Pappus bristles uniseriate, persistent, scabrous,numerous,connateatthebaseformingaringlikestructure. 8. Aster sikkimensrs Hook' f' (Fig' 6' K-S) mm x 0'25-0'3 mm' Cypsela homomorphic, nearly oblong' 0'8-0'9 towards the base' slightly blackish brown, straight, slightly narrowed pronrinent ribs' Cypsela surfacc compressed anterio-pJsteriorly, with 4 Glandular hairs absent' densely covered by acroscopic 'twin' hairs' natrow, completc ring (from Stylopodiunr absent. Carpopodium asymmetric, top ui.*; or strap like (from lateral same as the base of the cYPsel morphologicallY from the cells in 4-6 rows, thick-walled' PaP more or less free' mm long, reddish, thin, scabrous' numerous' 9. Aster stracheyi Hook' f' (Fig' 7' A-I) Cypselahomomorphic,oblong,2'2'2'3mmx0'5-0'6mm'brownish' ilose, with two prominent lateral ribs' acroscopic 'twin' hairs with ncarly dular hairs. Stylopodium very short m asymmetric, wide, comPletc ring diamcter nearly (from top view) or cup like (from lateral view), whitish, cells quite distinct same as the base of the cypsela. carpopodial vertically oricnted in 4-6 morphologically from the celis of cypselar wall; persistent, 5'25-5'5 nrnr long' rows, thick-walied. Pappus bristles uniseriate, less united at thc basc fornring brownish, thin, scabrous, numerous, more or a ring like structure. lo. (Fig' 7, K-S) Aster trinervius Roxb. ex D. Don var. trinervius olate, 1.6-1.7 mm x 0.5 mm' brown, ore towards the base, pilose, 5-ribbcd' acroscopic 'twin' hairs with -slightly ent. Stylopodium not so prominent' complete ring (from top view) or strap iameter nearly same as the base of the tinct morphologically from the cells of n 2-3 rows, thick-walled' Pappus bristles 493 .l f/ Fig. 6. A-J. Aster hinnlaicus. A. Cypsela, B. Apical part of cypsela, C. Basal part of cypsela, D. surface of rypsela, E. Glandular hair, F. Twin hair, G. Carpopodial cells, H. Basal part of pappus bristlc. I. Middlc part of pappus bristle, J. Apical part of pappus bristle, K-S. l. sikkinensis. K. Cypsela, L. Apical part of cypsela, M. Basal part of cypsela, N. Surface of cypsela, O. Twin hair, P. Carpopodial cells, Q. Basal part of pappus bristle, R. Middle part of pappus bristle, S. Apical part of pappus bristle. 494 s .l FI 8t Flg. 7. A-1. Aster stacheyi. A. Cypsela, B. Apical part of cypsela, C. Basal part of cypsela, D. Surface of cypscla, E. Glandular hair, F. Twin hair. G. Carpopodial cells. H. Basal part of pappus bristle, I. Middlc part of pappus bristle, J. Apical part of pappus bristle. K-S. lrinervius var. lrinervius. K. Cypsela, L. Apical part of cypsela, M. Basal part of cypsela, N. Surface of cypscla, O. Twin hair, P. Carpopodial cells, Q. Basal part of pappus bristlc, R. Middle partof pappus bristle, S. Apical part of pappus l. bristle. 495 uniseriate, persistent, 5.5-6 mm long, brownish, thin, scabrous, nunrcrous, more or less free. KEY TO THE SPECIES la. lb. 2a. 2b. 3a. 3b. Pappus biseriate and dimorphic ................ 2 Pappus uniseriate and homomorphic 4 Number of ribs 2; glandular hairs ......... Number of ribs 4; glandular hairs present ................. Cypsela 1.25-1.4 x 0.7{.8 lateral .... --. A.flaccidtr surface hair presenr on cypselar surface A. asteroiclcs ssp. fluc,c.idu.r ....... 5 ........................ 6 ribs 4: carpopodialcells oriented in 4-6 tires; pappus bristles 3.0 A. sikkimensis ................... Cypsela oblanceolate; ribs 5; carpopodial celts oriented in 2-3 tires; pappus bristles 5.55.5 mm long ..... A. trinertius var, trinervius 6a. Cypsela wide obovate; 3.25-3.35 x 1.7- 1.8 mm 6b. Cypsela oblong to oblanceolate; l.25-2.5 x 0.25-0.5 mm ........... .... A. alpirtus .........7 7a. Number of ribs 4; carpopodial cells horizontally oriented or vertically horizontally 7b. l fluc'c.idrr ssp. glunclulo.su.s hair absent on cypselar 5a' Cypsela oblong; mm long ... A. mm; ribs anterior-posterior in position Cypsela 1.8- 1.9 x 0.2-0.4 mrr; ribs 4a. Glandular 4b. Glandular 5b. absent oriented Number of ribs 2: corpopodialcells verticaily 8a. cypsela 1.25-1.4 8b. cypsela 2.4-2.5 oriented x 0.25-0.3 mm; corpopodial cells arranged bristles 4.04.5 mm long ........................ 9 in 5-? rires; pappus A. mm x 0.5-0.6 mm; corpopodiat bristles 5.0-5.5 mm and ................,.. g long cc[s albesc.ctts arranged in 2-3 rires; pappus .......-.-....A. hitnuluicus 9a' Tips of the twin hair conspicuously unequal; carpopodial cells arranged in 2-4 rows; pappus bristles 3.0-3.5 mm long ....... A. ageratoides ssp. alatopetiolatu 9b. Tips of the twin hair nearly equal; carpopodial cells arranged in 4- 6 rows; pappus bristles 5.5 mm 1ong............ .......... A. strachq.i DISCUSSION The cypselas in Aster L. have an uniform structure with nrinor variations in different species. 496 Cypselas are usually homomorphic, oblong to oblanceolatc, seldonr widc obovate as in A. alpinus (Fig 2A). The size of cypselas usually varies fronr L25-2.5 x 0.25-0.5 mm, whereas smallest cypsela has becn rccordcd in A sikkirttettsis (0.8-0.9 x 0.25-0.3 mnr) and largest in A. alpirtus (3:253.35 x 1.7-1.8 mrn). Cypsclas are olten dorsiventrally conrpresscd rvith 2 (5 specics) -4 ribs (4 spccies), seldom with 5 ribs as in A. trinen,irrs var. trinervius (Fig. 8 J). When nunrbcr of ribs is only 2 thcn thcsc arc lound at thc lateral sides of cypsela, whilc in A. asteroides ribs cxist in antcriopostcrior sides. Earlier, presence of different fornrs of cypsclar structurc havc been noticcd by Grau (1977) and Mukherjee (1991) frorn thc tribc Astercae. In all specics cypselar surfacc is adpresscd with nunrcrous trvin hairs. Tips of the thcse hairs arc distinctly unequal in A. ageratoides ssp. alatopetiolata (Fig. I D, F) or slightly unequal in A. flacc'idus, A. himalaicus, A. sikkimensis and A. trinervius var. Irirtervius or cqual (in rest of the species). Cypselar surface possesses biseriatc glandular hairs in studied 6 spccies, which are absent in A. asteroides (Fig. 3 A, D), A. flaccidus ssp.Jlaccidus (Fig 4 A, D); A. sikkintensis (Fig. 6 K, N) and A. lrinervius var. trinervius (Fig. 7 K, N). So, on the basic of structurc of cypselar hairs, the prcsent obscrvations are in consonancc with thc earlier rcport of Grau (1977) and Nesom ( 1994). "-Structure of stylopodium is not taxonomically significant. Carpopodiunr is morc or lcss identical, i.e., asymmctric, complctc ring-likc structurc. Suclr type of carpopodiunr has bcen reportcd by Haque & Godword ( 1984) and Mukhcrjec (1991) from other spccics of the genus Aster. Carpopodial cclls are usually oriented in2-6 tires, but thesc arc distributed upto 7 rows in A. albescens (Fig, lQ). Positive corrclation is observcd in thc oricntation of carpopodial cells among the studies species. On this basis, carpopodia can bc divided into following 3 categories: (i) Carpopodial cclls arc vcrtically orientcd, c.9., A. ageratoides, A. alpittus, A. flaccidus ssp. glandulosus and A. stracheyi; (ii) Carpopodial cells are horizontally oricntcd, c.g., A. albescens, A. asteroides, A. sikkintensis and l. !rinervius; (iii) Carpopodial cells are both vcrtically and horizontally oricntcd, e.g., A. Jlaccidus ssp. flaccidus and A. himalaicus. Among the studied spccies, two (1. asleroides, A. Jlaccidrrs) havc distinctly dimorphic, two rows of pappus. Outer row of pappus is reprcscntcd by many, pcrsistent, thick, scales of 0.4-0.7 n'rm long and innir row consists of numerous, persistent, scabrous, thin bristlcs of 2.5-4.0 nrnr 497 , 0'S rh Yyt O'2 rnm H Flg. 8. Diagrammatic reprcsentation of cross section of cypselas. A. Aster ugeratoiclcs ssp. ala.topetiolata B. A. albescens, C. A alpinus, D. A. asteroides, E. A. flaicidus ssp. flaccidus' F' A. flaccidus ssp. glandulosus, G. A. hiualaicrr.r, H. A. sikiitnetrsrs, L r4. slracheyi, J. A. trinen,irr.s var. trinervius. long. Seven studied species of Aster have uniseriatc, persistcnt, homomorphic, thin, scabrous bristles of 3.0-6.5 nrnt long. The cypselas of nine of the investigated species of Aster can bc distinguished from one another and a key for identification is preparcd on the basis of present observation. So, the diacritical fcatures of cypsclas can be used for easy recognition of taxa at the specific level too. 498 ACKNOWLEDGEMENTS The authors are grateful to the Director and curator of the Herbariunr, Conservatoire et Jardin Botaniques Geneve, Gcneva, for supplying plant nraterial. LITE'RATIJRE CTTED Bremer, K. 1987. Tribalinterrelationship of the Astcraceae. Cludistic's 3:210-253. I. 1977. Astercac-systematic review. In: Heyrvood, V. H.: Harbornc, J.B. & Turncr. B.L. (Eds.), Tlte biologl, and chemistty of the Conrpositae. Acadenric Press, London. pp.539-565. Crau, Hajra, P.K.; Rao, R.R.; Singh, D.K. & Uniyal, B.P. (Eds.). 1995. Floru 13, BSI, Calcutta. o.[ Indiu. Vol. l2- Haque. M.Z. & Godward, M.B.E. 1984. New Records of thc carpopodium in Conrpositac and its taxonomic use. Bot" I. Linn. Soc. 89: 32 l-340. Kynclova, M. 1970. Comparative morphology of achenes of the tribe Anthemideac Cass. (Asteraceae) and its taxonomic significance. Preslia 42: 33-53. Mabberley, D.l. 1997. The PIant-Boo&. Cambridge University Press, Cambridgc. Mukherjee, S.K. 1991. Carpological Studies in Composilae. Ph.D. thcsis, Kalyani Universiry, Kalyani. Nesom, G.L. 1994. Subtribal classfication of the Astereae (Asteraceac). Ph1:tologia 76: t93-274. Yelez, M.C. 1981. Carpologische (Jntersuchungen an amerikanischen Astcrcac (Compositae). Mitt. Bot. Staat. Munchen l?: l-170.