Karyomorphology of Heptacodium ( s.str.) and Its Phylogenetic Implications Author(s): Zhao-Yang Zhang, Zhe-Kun Zhou and Zhi-Jian Gu Reviewed work(s): Source: Taxon, Vol. 51, No. 3 (Aug., 2002), pp. 499-505 Published by: International Association for Taxonomy (IAPT) Stable URL: http://www.jstor.org/stable/1554862 . Accessed: 12/10/2012 06:06

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http://www.jstor.org TAXON 51 * August 2002: 499-505 Zhang & al. * Karyomorphology of Heptacodium

KARY*L*

Karyomorphology of Heptacodium (Caprifoliaceae s.str.) and its phylogenet- ic implications

Zhao-Yang Zhang, Zhe-Kun Zhou & Zhi-Jian Gu

InstituteofBotany, The ChineseAcademy ofSciences, Kunming,Yunnan, 650204, China.E-mail: spiraea_evol @yahoo.com,;zhouzk@public. km.yn. cn; [email protected]. cn (authorfor correspondence).

A karyomorphologicalstudy of the species Heptacodiummiconioides and five species in Caprifoliaceaeof pre- sumably related genera [Abelia and Depelta (Linnaeeae);Lycesteria and Lonicera (Caprifolieae); (Diervilleae)] reveals similarities in some karyological features such as structureof interphasenuclei, chro- mosome size, and condensationbehaviour of chromosomesduring mitotic prophase.However, differences bet- ween them in chromosomebase numberand morphologyof metaphasechromosomes have also been revea- led. The chromosomenumber of Heptacodium2n = 28 is unique in Caprifoliaceae,presumably having resul- ted from polyploidizationfollowing hybridizationbetween two ancestralspecies (possibly with chromosome base numberx = 8 or 9) bearingcharacters of tribes Caprifolieaeand Linnaeeae,respectively. The phylogene- tic position of Heptacodiumis discussed based on combinationof karyomorphologyand previous morpholo- gical and moleculardata.

KEYWORDS:Caprifolieae, Heptacodium, karyomorphology, Linnaeeae.

Several other morphological studies of inflorescences INTRODUCTION (Troll & Weberling,1966; Weberling,1966) also indicat- Heptacodium Rehder (Caprifoliaceae s.str.) is a ed that Heptacodium is related to tribe Caprifolieae. with its has been in different monotypic genus single species, H. miconioides, Heptacodium, therefore, placed being endemic to a narrowarea in easternChina (Rehder, tribes, sometimes in Linnaeeae (Hara, 1983; Takhtajan, 1916; Hsu, 1988; Tang & Li, 1994; Mabberley, 1997) . 1987; Hsu, 1988; Tang & Li, 1994), and sometimes in Airy Shaw (1952), however, considered the genus to Caprifolieae (Fukuoka, 1972; Donoghue, 1983). More- contain two species. over, Golubkova (1965) suggested that Heptacodium Heptacodium contains a puzzling combination of should be treatedin a separatetribe Heptacodieae,stress- morphological characters. There is a shared trend in ing differences from Linnaeeae by the former'stwo six- Heptacodium and genera of tribe Linnaeeae toward flowered whorls of flowers with elongate corollas, and reduction of ovary and fruit, with three carpels (four in from Caprifolieaeby the former's ovary (three carpels, Dipelta), of which two are sterile, and with a single-seed- only one being fertile) and a single-seeded fruit bearing ed fruit (two-seeded in Dipelta; Pyck & al., 1999). The an accrescentpersistent calyx. A recent molecularphylo- fruit of Heptacodiumwith its accrescentpersistent calyx genetic study (Pyck & Smets, 2000), mainly based on shows similarities with fruits of Abelia (Rehder, 1916). ndhF data, showed Heptacodium as sister to the clade Further,its habit and bark are reminiscentof Dipelta as consisting of Lycesteria,Lonicera, Symphoricarposand well as Kolkwitzia (Koller, 1986; Coombes, 1990). On Triosteum, but only weakly supported. Results of all the other hand, Heptacodium shows similarities with analyses supported an unresolved basal position for genera of tribe Caprifolieae, especially with regard to Heptacodiumamong Caprifoliaceaes.str. The exact phy- inflorescence structure.Rehder (1916) mentioned in the logenetic position of Heptacodiumremains to be deter- original descriptionthat the six-flowered whorls consist- mined. ing of two three-floweredcymes of Heptacodiumcould A comparative karyomorphological study of be analogous to those of Lonicera subg. Caprifolium. Heptacodium and related genera might contribute to Airy Shaw (1952) consideredthat the floral arrangement understandingthe phylogeny of Heptacodium.Ten of the of two six-flowered whorls of flowers in Heptacodiumis thirteengenera in Caprifoliaceaes.str. alreadyhave been reminiscent of some species of Lycesteria, and that the investigatedeither cytologically or karyomorphological- leaves of Heptacodium resemble those of L. formosa ly (Bedi & al., 1982; Love & Love, 1982; Sokolovskaya quite closely, apart from their trinerved condition. & Probatova, 1985; Probatova& Sokolovskaya, 1988;

499 Zhang & al. 9 Karyomorphology of Heptacodium TAXON 51 * August 2002: 499-505

Lavrenko & Serditov, 1991; Benko-Iseppon & ulum.Small deeply stained spheroid granules are evenly Morawetz,2000). Because no previousreports regarding dispersedthroughout the nuclei(Fig. 1A-F). karyomorphologyof Heptacodiumhave been available Condensation behaviour. - The six genera so far,this paperaims to compareHeptacodium with its studiedall displayproximal-early condensing chromo- relatedgenera karyomorphologically for phylogenetic somes from mitoticprophase to metaphase.Proximal insights. regions of chromosomesare deeply stained showing earlycondensation, while distalregions of chromosome arms are extended,showing late condensation(Fig. MATERIALSAND METHODS 1G-L). Chromosome size and morphology. - The materialsstudied with voucherspecimens are Heptacodium has relatively smaller chromosomes shownin Table1. Investigatedplants came eitherfrom (0.7-2.7 glm)than the othergenera studied (1.3-4.2 glm; naturalpopulations or frombotanical gardens and were Figs. 2, 3; Table 3). With regardto architectureof cultivatedin the BotanicalGarden at KunmingInstitute metaphasechromosomes, divergence between Hepta- of Botany,Chinese Academy of Sciences. codiumand the other generacan be observed.Most Roottips were pretreated in 2 mMhydroxyquinoline metaphasechromosomes of Heptacodiumare with sub- median,subterminal, and terminalpoint centromeres. chromosomearchitecture similarin Table 1. List of Voucher Although appears investigated species. specimens the other most chromosomeshave medianand are deposited in KUN. KB = Kunming Botanical Garden, genera, Kunming Institute of Botany, Chinese Academy of submediancentromeres, with terminal centromeres Sciences. ZZY= Zhang Zhao-Yang. completelylacking (Figs. 2, 3; Tables2, 3). Heptacodium also has a of chromosomeswith arm Heptacodiummiconioides Rehd. China,Zhejiang 1999, ZZY 045 higherpercentage ratioover 2.0 andRLR (relative length ratio between the Caprifolieae and shortest over 3.0 Thunb. China,Yunnan, 1999, ZZY049 longest chromosomes) (Tables2, Loniceriajaponica It is thatthe first of chromosomesin LycesteriaformosaWall. China,Yunnan, 1999, ZZY048 3). noteworthy pair Diervilleae Heptacodiumis prominentlymuch larger than the second one, whereaschromosomes in in Weigelacoraeensis Thunb. KB, 1999, ZZY050 vary gradually length Linnaeeae Abelia,Dipelta, Lycesteria, Lonicera, and Weigela. Abeliaparvifolia Hemsl. China,Yunnan, 1999, ZZY046 ZZY Depeltayunnanensis Franch. China,Yunnan, 1999, 047 DISUSO Multipleevidence indicates that Heptacodium shares at roomtemperature for 2 h, andthen fixed in Carnoy's affinities with tribes Caprifolieaeand Linnaeeaein liquidfixative (3 ethanol: 1 glacialacetic acid) at 40 for Caprifoliaceaes.str. (Rehder,1916; Airy Shaw, 1952; 30 minutes.After maceration in IN hydrochloricacid at Metcalfe, 1952; Troll & Weberling,1966; Weberling, 60' for 5 minutes,material was stainedwith Carbol 1966; Hara,1983; Koller, 1986; Hsu, 1988;Coombes, Fuchsinand squashed for observation in 45%acetic acid. 1990; Tang& Li, 1994;Mabberley, 1997; Pyck & al., Five individualswere investigatedfor each species. 1999).This relationship is confirmedby recentmolecu- Chromosomemeasurements were obtainedfrom the lar phylogeneticstudies (Backlund & Pyck, 1998;Pyck photographsof the best 5 mitoticmetaphase plates of & Smets,2000), as well as by the presentkaryomorpho- eachspecies. Haploid idiograms were obtained by draw- logicalcomparisons. Heptacodium and other representa- ing in accordancewith the karyotypeparameters. tives of Caprifoliaceaes.str. all exhibitrelatively smaller Terminologyconcerning condensation behaviour of chromosomes(0.6-4.2 jlm; Table3; Benko-Iseppon& chromosomesduring mitotic prophase follows Morawetz Morawetz,2000), semi-reticulateinterphase nuclei, and & Samuel(1988). Descriptionof karyotypesfollows proximal-earlycondensing chromosomes (Fig. 1; see Levan (1964). Karyotypesymmetry was classified Benko-Iseppon& Morawetz,2000, forfurther karyolog- accordingto Stebbins(1971). ical informationof Caprifoliaceaes.str.). Viburnum and Sambucus,two generawhich are now excludedfrom Caprifoliaceaes.str., show much largerchromosomes lack of heterochromatic euchro- RESULTS (2.6-7.1 gm), blocks, maticinterphase nuclei, and continuous condensing pat- Interphase nuclei. - All six generaexhibit semi- terns from mitotic prophaseto metaphase(Benko- reticulateinterphase nuclei with a finelygranulated retic- Iseppon& Morawetz,2000). It is thereforeclear that

500 TAXON 51 e August 2002: 499-505 Zhang & al. * Karyomorphology of Heptacodium

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Fig. 1. Interphase nuclei (A-F) and mitotic pro-metaphase chromosomes (G-L) of Heptacodium and its related genera. A & G, Heptacodium miconioides; B & H, Depelta yunnanensis; C & I, Lycesteria formosa; D & J, Abelia parvifolia; E & K, Weigela coraeensis; F & L, Lonicera japonica.

Heptacodiumbelongs in Caprifoliaceaes.str. or x = 9. The haploidchromosome number of Hepta- Ten of the thirteengenera in Caprifoliaceaes.str., codium is x = 14. There is thereforegood reasonto with which Heptacodiumshares affinities, have been believethat Heptacodium is of polyploidorigin, with the cytologicallyinvestigated (Bedi & al., 1982; Lve & originalbase number x = 7. Consideringthe specialcom- Love, 1982; Sokolovskaya & Probatova, 1985; binationof morphologicalcharacters of Heptacodium,a Probatova& Sokolovskaya,1988; Lavrenko & Serditov, hypothesiscan be developedthat the genusoriginated by 1991;Benko-Iseppon & Morawetz,2000). The chromo- polyploidizationfollowing hybridizationbetween two somebase numbers of all studiedspecies are either x = 8 ancestralspecies (possibly with chromosome base num-

501 Zhang & al. * Karyomorphology of Heptacodium TAXON 51 * August 2002: 499-505

A

46

..1.

'l d~dIF 1* 9*

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Fig. 2. Mitotic metaphase chromosomes of Heptacodium and related genera. A, Depelta yunnanensis; B, Heptacodium miconioides; C, Abelia parvifolia; D, Lycesteria formosa; E, Lonicera japonica; F, Weigela coraeensis. berx = 8 or 9) bearingcharacters of tribesCaprifolieae arerelatively smaller than those of relatedgenera (Fig. 2; and Linnaeeae,respectively. The asymmetrickaryotype Table3). Thechange of basechromosome number from of Heptacodiumfeatured by subterminaland terminal x = 8 or 9 to x = 7 can be readilyexplained by the dislo- chromosomes(Fig. 3D) couldhave been derived from a cationhypothesis (Stebbins, 1971), in whichsuccessive symmetrickaryotype of polyploidorigin, possibly being unequaltranslocations progressively increase differences producedby successivepericentric inversions and by in relative size between chromosomesin ancestral unequaltranslocations during modification after poly- Heptacodium,producing extremely small chromosomes ploidization.Losses of chromosomalsegments contain- or centric fragmentscontaining no essential genetic ing geneticmaterial in duplicatecould also have been material,and leading finally to aneuploidreduction. involved in the process of modificationafter poly- The systematicposition of Heptacodiumwithin ploidization,because the chromosomesof Heptacodium Caprifoliaceaes.str. has long been disputed.Morpho-

502 TAXON 51 * August 2002: 499-505 Zhang & al. * Karyomorphology of Heptacodium

Table 2. The karyomorphological parameters of Heptacodium and related species. Each value is based on the mean of measurements of the best five plates in each species. Following abbreviations are used: TL, total chromosome length; AR, arm ratio (LIS); Cl, centromeric index (100S/TL); m, median region; sm, submedian region; st, subterminal region; t, terminal point; *, chromosome with satellite. Chromosome pairs are assigned Roman numerals. Pair no. TL AR CI Type Pair no. TL AR CI Type Heptacodiummiconioides I 6.8 3.0 25.0 sm VIII 3.1 2.9 25.8 sm II 4.9 3.1 24.5 st IX 3.0 8 0.0 t III 4.7 3.3 23.4 st X 2.9 1.6 37.9 m IV 4.6 1.7 37.0 sm XI 2.9 6.3 13.8 st V 4.0 3.0 25.0 sm XII 2.6 1.4 42.3 m VI 3.4 3.3 23.5 st XIII 2.5 8 0.0 t VII 3.4 8 0.0 t XIV 2.0 8 0.0 t Abeliaparvifolia I 5.0 1.1 48.0 m IX 3.0 1.3 43.3 m II 4.1 2.4 29.3 sm X 2.9 1.4 41.4 m III 3.9 1.1 48.7 m XI 2.8 2.1 32.1 sm IV 3.8 1.5 39.5 m XII 2.6 1.4 42.3 m V 3.6 1.0 50.0 M XIII 2.6 2.7 26.9 sm VI 3.5 1.7 37.1 sm XIV 2.4 1.2 45.8 m VII 3.3 1.2 45.5 m XV 2.2 3.4 22.7 st VIII 3.1 2.4 29.0 sm XVI 2.0 1.9 35.0 sm Depeltayunnanensis Lycesteriaformosa I 7.9 1.7 36.7 sm I 9.8 2.2 31.6 sm II 7.6 2.2 31.6 sm II 6.3 2.2 31.7 sm III 6.5 2.2 32.3 sm III 6.0 2.5 28.3 sm IV 5.9 2.3 30.5 sm IV 5.9 1.5 40.7 m V 5.7 1.3 43.9 m V 5.2 2.7 26.9 sm VI 5.2 2.5 28.8 sm VI 4.9 1.3 42.9 m VII 4.7 1.9 34.0 sm VII 4.2 3.7 21.4 st VIII 3.9 2.3 30.8 sm VIII 4.1 1.2 46.3 m IX 3.5 2.9 25.7 sm IX 3.9 2.0 33.3 sm Lonicerajaponica I 5.1 4.1 19.6 st X 2.9 1.1 48.3 m II 4.0 3.0 25.0 sm XI 2.6 1.2 46.2 m III 3.8 1.7 36.8 sm XII 2.6 1.2 46.2 m IV 3.8 2.2 31.6 sm XIII 2.2 1.2 45.5 m* V 3.7 2.4 29.7 sm XIV 2.2 1.2 45.5 m VI 3.2 2.2 31.3 sm XV 2.1 1.3 42.9 m* VII 3.1 1.6 38.7 m XVI 2.1 1.3 42.9 m VIII 3.0 1.5 40.0 m XVII 1.9 1.4 42.1 m IX 2.9 1.2 44.8 m XVIII 1.9 1.1 47.4 m Weigelacoraeensis I 7.6 1.9 34.2 sm VI 5.1 1.4 41.2 m II 7.2 1.8 36.1 sm VII 4.5 2.5 28.9 sm III 6.5 2.0 33.8 sm VIII 4.3 2.3 30.2 sm IV 5.5 1.9 34.5 sm IX 4.1 2.2 31.7 sm V 5.3 2.1 32.1 sm logically,Heptacodium shares some characteristicswith ture,complicate the placementof Heptacodiumin either tribesLinnaeeae and Caprifolieae,and can be regarded of the two tribes(Golubkova, 1965). All generaof tribes as a link betweenthese two otherwisedissimilar tribes Linnaeeaeand Caprifolieae have been investigated cyto- (Tang& Li, 1994).However, differences of Heptacodi- logically. Chromosomebase numbersare variablein umfrom genera of Linnaeeaein inflorescencestructure, Linnaeeae, being x = 8 (Abelia, Kolkwitzia,Linnaea) or andfrom those of Caprifolieaein ovaryand fruit struc- x = 9 (Abelia, Symphoricarpos).All species of Lycesteria

503 Zhang & al. * Karyomorphology of Heptacodium TAXON 51 * August 2002: 499-505

Table 3. Karyomorphological features of Heptacodium and relatives. RLR, relative length ratio (longest/shortest); P, percentage of chromosomes with arm ratio over 2:1; x = chromosome basic number; m, median region; sm, submedi- an; st, subterminal; t, terminal; T, terminal point; SAT, satellite; *, chromosome with sattelite. Chromosome pairs are assigned Roman numerals. Chromosomesize Symmetry Tribe Species Karyotypeformula (min.-max.in pm) RLR P class x Heptacodium 2n = 4m (X, XII)+ 6sm(I, IV,V) 0.7-2.7 3.4 78.6% 3B 7 miconioides + 10st(II, III,VI, VIII,XI) + 8T (VII,IX, XIII,XIV) Linnaeeae Abeliaparvifolia 2n = 2m (V) + 16m(I, III,IV, VII, IX, 1.4-3.4 2.5 31.3% 2B 8 X, XII,XIV) + 12sm(II, VI, VIII, XI, XIII,XVI) + 2st (XV) Depeltayunnanensis 2n = 2m (V) + 16sm(I, II, III,IV, 1.8-4.1 2.3 66.7% 3B 9 VI, VII,VIII, IX) Caprifolieae Lycesteriaformosa 2n = 6m (IV,VI, VIII)+ 1.8-4.2 2.5 55.6% 3B 9 10sm(I, II, III,V, IX) + 2st (VII) Lonicerajaponica 2n = 24m(4 SAT)VII, VIII, IX, X, XI, XII, 1.3-3.7 2.7 27.8% 2B 9 XIII*,XIV, XV*, XVI, XVII, XVIII) + 10sm(II, III, IV, V, VI) + 2st (I) Diervilleae Weigelacoraeensis 2n = 2m (VI) + 16sm(I, II, III,IV, 2.0-3.8 1.9 44.4% 2A 9 V, VII,VIII, IX) and Lonicerain Caprifolieaeshare the same chromo- Heptacodiumis karyologicallydifferent from genera of some base numberx = 9. Fromthe perspectiveof chro- the two tribes,having an untypicalbimodal karyotype mosomebase numberonly, Heptacodiumis closer to with most chromosomeshaving centromeresthat are generaof Linnaeeaethan to Caprifolieae.Nevertheless, submedian,subterminal, and terminal. The karyotypeis relativelystable and similar in generaof tribesLinnaeeae andCaprifolieae, most chromosomesbeing median and A 000 submedian with terminalcentromeres D000DD (chromosomes being completelylacking; Figs. 2, 3; Tables2, 3; see Benko-Iseppon& Morawetz,2000, for generalkaryo- B 0E0100]0E0fl morphologicalfeatures of Caprifoliaceaes.str.). The placementof Heptacodiumin eitherof the two tribes, therefore,is alsonot resolved by thekaryomorphological differencesbetween them. In addition,although the phy- trees constructedwith ndhF data oo logenetic sequence o iLL0o[ _o show Heptacodiumas sisterto the clade consistingof D 0ll 0].c.C D Lycesteria, Lonicera, Symphoricarpos and Triosteum (Pyck & Smets,2000), this topologywas weakly sup- ported, and an unresolved basal position for Heptacodiumamong Caprifoliaceae s.str. was also men- E 00000000ooI0000o tionedby the authors.In view of all these facts,Hepta- codiumoccupies a specialposition in Caprifoliaceae s.str. The proposalby Golubkova(1965) that Hepta- codiummerits being treatedas an independenttribe, Heptacodieae,seems desirable. Further evidence is nec- essary,however, to test this hypothesis.

Fig. 3. The haploid idiograms of Heptacodium and related genera (all same scale). A, Weigela coraeensis; B, ACKNOWLEDGEMENTS Depelta yunnanensis; C, Lycesteria formosa; D, We are to Profs. Li Xiwen, Guo Heptacodium miconioides; E, Abelia parvifolia; F, grateful YangQiner, Qinfeng Lonicera japonica. and Sun Hangfor valuablecomments and suggestions. Thanks are

504 * TAXON 51 * August 2002: 499-505 Zhang & al. Karyomorphology of Heptacodium

numbersin the vascular from the Primoryeterrito- also due to Tod for This Prof. Stuessy language improvement. ry, the Amur River basin, northKoryakia, Kamchatka and was the NationalNatural Science study financiallysupported by Sakhalin.Bot. furn. 73: 290-293. Foundation of China (39930020), the Chinese Academy of Pyck, N., Roels, P. & Smets, E. 1999. Tribalrelationships in Sciences ProjectSTZ-1-04, National Natural Science Foundation Caprifoliaceae:evidence from a cladistic analysis using ndhF Pl. 69: 145-159. of China Project 39770065 and National Natural Science sequences. Syst. Geogr N. & Smets, E. 2000. A searchfor the Foundationof YunnanProject 99C0073M. Pyck, phylogeneticposi- tion of the seven-son flower (Heptacodium,): combining molecular and morphological evidence. Pl. Syst. Evol. 225: 185-199. LITERATURECITED Rehder, A. 1916. Caprifoliaceae.Pp. 617-619 in: Sargent, C. S. (ed.), Plantae Wilsonianae 2. Arnold Arboretum, Airy Shaw, H. K. 1952. A second species of the genus Boston. Heptacodium Rehd. (Caprifoliaceae). Kew Bull. 7: Sokolovskaya, A. P. & Probatova, N. S. 1985. Chromosome 245-246. numbers in the vascular plants from the Primoryeterrito- Backlund, A. & Pyck, N. 1998. Diervillaceae and ry, Kamchatkaregion, Amur valley and Sakhalin. Bot. Linnaeaceae,two new families of caprifolioids. Taxon47: Zurn. 70: 997-999. 657-661. Stebbins, G. L. 1971. Chromosomal Evolution in Higher Bedi, Y. S., Bir, S. S. & Gill, B. S. 1982. Cytological studies in Plants. EdwardArnold, London. certain woody members of family Caprifoliaceae.J. Tree Takhtajan, A. L. 1987. Systema Magnoliophytorum.Nauka, Sci. 1: 27-34 Leningrad. Benko-Iseppon, A. M. & Morawetz, W. 2000. Viburnales: Tang, Y.-C. & Li, L.-Q. 1994. The phytogeography of cytological featuresand a new circumscription.Taxon 49: Caprifoliaceaes.str. with its implications for understand- 5-16. ing eastern asiatic flora. Acta Phytotax. Sinica 32: Coombes, A. J. 1990. Heptacodiumjasminoides the Chinese 197-218. seven-son flower in Britain.Kew Mag. 7: 133-138. Troll, W. & Weberling, F. 1966. Die Infloreszenzen der Donoghue, M. J. 1983. The phylogenetic relationships of Caprifoliaceen und ihre systematische Bedeutung. Abh. Viburnum.Pp. 143-166 in: Platnick, N. I. & Funk, V. A. Akad Wiss.Lit. Mainz. Math. Naturw.Kl. 4: 455-605. (eds.), Advances in Cladistics 2. Columbia Univ. Press, Weberling, F. 1966. Zur SystematischenStellung der Gattung New York. HeptacodiumRehd. Bot. Jahrb. 85: 253-258. Fukuoka, N. 1972. Taxonomic study of the Caprifoliaceae. Mem. Fac. Sci. Kyoto Univ.Ser. Biol. 6: 15-58. Golubkova, V. 1965. De genere HeptacodiumRehd. e familia Caprifoliaceae.Nov. Syst. Pl. Vas.2: 230-236. Hara, H. 1983. A revision of Caprifoliaceaeof Japanwith ref- erence to allied plants in other districtsand the Adoxaceae. Ginkgoana 5: 1-336. Hsu, P.-S. 1988. Caprifoliaceae.Pp. 1-264 in: Chien, C.-S. & Chen, H.-Y. (eds.), Flora Reipublicae Popularis Sinicae, vol. 72. Science Press, Beijing. Koller, G L. 1986. Seven-son flower from Zhejiang:introduc- ing the versatile ornamental shrub Heptacodiumjasmi- noides. Arnoldia 46: 3-13. Lavrenko, A. N. & Serditov, N. P. 1991. Chromosomenum- bers in some plant species from the southwestof the Komi ASSSR. Bot. Zurn. 76: 769-771. Levan, A., Fedga, K. & Sandberg, A. A. 1964. Nomenclature for centromericposition on chromosomes. Hereditas 52: 201-220. Live, A. & Live, D. 1982. In IOPB chromosome number reports. Taxon31: 120-126. Mabberley, D. J. 1997. ThePlant-Book, a Portable Dictionary of the Vascular Plants. Cambridge Univ. Press, Cambridge. Metcalfe, C. R. 1952. Notes on the anatomyof Heptacodium. Kew Bull. 7: 247-248. Morawetz, W. & Samuel, R. 1988. Karyological patternsin the Hamamelidae. Pp. 129-154 in: Crane, P. & Blackmore, S. (eds.), Evolution, Systematics and Fossil History of the Hamamelidae. Vol. 1. Introduction and "lowerHamamelidae ". ClarendonPress, Oxford. Probatova, N. S. & Sokolovskaya, A. P. 1988. Chromosome

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