Seed Morphology in Some European Aconites (Aconitum,

7/27/2019 Seed Morphology in Some European Aconites (Aconitum,

1/9

P1. Sy st. Ev ol. 1,15, 193 --20 1 (1984) Plnnt V.stemntitsund Eonlution by Springer-Verlag 1984

Seed Morphology in Some European Aconites (Aconi tum,Ran un culaceae)

B yElsa M. Cappelletti and Livio Poldini

(Received July 18, 1983)

Key Words: Angiosperms, Ranunculaceae, Aconitum.--Seed morphology,seed coat SEM microcharacter is t ics , taxonomic impor tance, adaptat iveecological significance.Abstract: The seed coat morphology, inves t igated in taxa representat ive ofthe main Europea n groups of Aconitum, are in good agree men t with the curren ttax on om y of the genus. The seed coat microcharacteris t ics (w arty epidermalcells) are ve ry con stant. There is a tren d for the reduction of longitudinal wingson the edges concomitant with the development o f r idges and t ransverse wingson the faces. Ano ther morphological progression leads from smo oth to ruguloseand eventually to transverse wing-bearing seed faces. A working hypothesissuggests an ecological ada pta tive significance to these changes.

Ow ing to the i r g re a t co ns ta nc y ( s t r es sed b y DAvis & HEYWOOD 1963),f e a t u r es o f s e ed m o r p h o l o g y p o t e n t i a l l y h a v e g r e a t t a x o n o m i c v a l u e(STEBBINS 1974) . Th is a l so app l ies to Aconitum an d i t s i n f r ag en e r i cc las s i f i ca t ion (GAYER 909 , TUTIN & MERXMULLER 1964 , SEITZ 1969 ). W eh a v e f u r t h e r i n v e s t i g a t e d t h e s e e d m o r p h o l o g i c a l f e a t u r e s o f t h e g e n u s ,t a k i n g i n t o a c c o u n t s e e d c o a t m i c r o c h a r a c t e r i s t i c s ( b y SE M ), i n a na t t e m p t t o e v a l u a t e t h e i r t a x o n o m i c s i g n i f i c a n c e a t t h e i n f r a g e n e r i c a sw e l l a s a t t h e i n f r a s p ec i f i c l ev e l .

Materials and MethodsNom enclature within Aeonitum napellus L. s. 1. is acc ord ing to SmTz (1969),and for the remaining groups according to TUTI~T& MERXMULLER 1964).Ripe seeds from specimens repres entativ e o f all the main groups described byT~ZTIN& MEI~XMULLER 1964) within the genus Aconitum for Europe have beenstudied:

13"


2/9

1 9 4 E . M . C A P P E L L E T T I & L . POLD~XI:

1 . A c o n i t u m a n t h o r a L . : w i l d s p e c i m e n s f r o m t h e C o n s e r v a t o i r e e t J a r d i nB o t a n i q u e s d e l a V i l l e d e Ge n ~ v e ( G) , S wi t z e r l a n d ;2 . A c o n i t u m n a p e l lu s g r o u p :2.1. A . n a p e l l u s L . s u b s p , t a u r i c u m (WuLs.) GAYEa: wi ld p lan t s f rom theC a r n i e A l p s a n d M r . G e n e r o s o ( L o m b a r d P r e - A l p s ) , I t a l y ;2.2. A . n a p e l l u s L . s u b s p , h i a n s (RmcHE~m) GAYS~: cu l t iv a te d p la n ts f romt h e Z a k t l a d F a r m a k o l o g i i , P r a c o w n i a A g r o t e c h n i k i , K r a k d w ( P o l a n d ) ;2.3. A . n a p e l l u s L . s u b s p , n e o m o n t a n u m (WuLF.) GAYE~: wi ld p la n t s f romVa l S a s s i n a , We s t e r n A l p s , I t a l y ;3 . A c o n i t u m v a r i e g a tu m g r o u p :3.1. A . v a r i e g a t u m L . : w i l d p l a n t s f r o m M t . Na n o s , S l o v e n i a , Yu g o s l a v i a ;3.2. A . p a n i c u l a t u m L AM .: w i l d p l a n t s f r o m t h e C a r n i c A l p s , I t a l y ;3.3. A . a n g u s t i fo l i u m B E aN H .: w i l d p l a n t s f r o m t h e J u l i a n A l p s a n d P r e - A l p s ,I t a l y .4 . A c o n i t u m v u l p a r ia g r o u p :4.1. A . v u l p a r i a R E IC g ENB .: w i l d p l a n t s f r o m t h e C o n s e r v a t o i r e e t J a r d i nB o t a n i q u e s d e l a V i l l e d e Ge n ~ v e ( G) , S wi t z e r l a n d ;4 . 2 . A . la m a r c k i i R m o ~ E ~ m : w i l d p l a n t s f r o m t h e C a r n i c A l p s , I t a l y .V o u c h e r s p e c i m e n s - - a s f a r as a v a i l a b l e - - h a v e b e e n d e p o s it e d i n t h eh e r b a r i u m o f t h e I n s t i t u t e o f B o t a n y , U n i v e r s i t y o f T r i es t e ( T S B ).T h e s e e d s we r e c o a t e d w i t h g o l d i n a n E d w a r d s S 1 50 A S p u t t e r C o a .te r a n do b s e r v e d u n d e r a S c a n n i n g E l e c t r o n M i c ro s c o p e C a m b r i d g e S t e r e o s c a n 2 5 0 a tt h e a c c e l e ra t i n g v o l t a g e o f 2 5 k V a t t h e C e n t r o U n i v e r s i ta r i o G r a n d iA p p a r e c c h i a t u r e S c i en t if ic h e ( C U G A S ) o f t h e U n i v e r s i t y o f P a d o v a .

Resu l t s

T h e s e ed s o f a ll t h e i n v e s t i g a t e d A c o n i t u m s p e c i e s a n d s u b s p e c i e s a r et r i a n g u l a r a n d p y r a m i d a l . A b a se , a t t h e c e n t e r o f w h i c h t h e r e g io n o f t h eh i l u m i s f o u n d , a n d t h r e e f a c e s c a n b e d i s t i n g u i s h e d . O n t h e t h r e e e d g e s ,l o n g i t u d i n a l w i n g s m a y b e p r e s e n t .

A s r e g a r d s t h e l o n g i t u d i n a l w i n g s , t h e f o l lo w i n g b a s i c se e d t y p e s w e r ef o u n d :- p r e s e n c e o f t h r e e l o n g i t u d i n a l w i n g s o f c o m p a r a b l e s iz e;- - p r e s e n c e o f t h r e e l o n g i t u d i n a l w i n g s , o n e o f w h i c h is d i s t i n c t l y m o r e

d e v e l o p e d t h a n t h e o t h e r t w o ;- p r e s e n c e o f o n l y o n e l o n g i t u d i n a l w i n g ;- - l o n g i t u d i n a l w i n g s a b s e n t .F i g s . 1 - 1 2 . - - F i g s . 1 4 . A c o n i t u m a n th o ra . - - F i g . 1 . s e e d w i t h l o n g i t u d i n a l w i n g so f c o m p a r a b l e s iz e o n t h e e d g e s , x 1 5 . - - F i g s . 2 , 3 . e p i d e r m a l c e lls w i t h r o u n d -topped tuberc les . F ig . 2 . x 50 ; F ig . 3 . x 150 . - -F igs . 4 , 5 . a l igned tuberc les ona d j a c e n t c e lls . F i g . 4 . 5 0 ; F i g . 5 . x 1 5 0 . - - F i g . 6 . w a r t y c e ll o r n a m e n t a t i o n ,x 25 0. - - F i g . 7 . s m o o t h c e lls o n t h e t o p o f l o n g i t u d i n a l w i n g s , x 1 5 0 . - - F i g . 8 .s m o o t h c ells o f t h e h i l u m r e g i o n , 1 0 0. - - F i g . 9 . A . n a p e l l u s s u b s p , h i ans : o n el o n g i t u d i n a l w i n g (r ig h t ) m o r e d e v e l o p e d t h a n t h e o t h e r t w o , x 2 0 . - - F i g s . 1 0 -1 l . A . n a p e l l u s s u b s p , t a u r i c u m . - - F i g . 10. r idges on the f aces , x 70 . - -F ig . 11 .s m a l l t r a n s v e r s e e x p a n s i o n , x 2 5 0 . - - F i g . 1 2. A . n a p e l l u s s u b s p , h i ans :t r a n s v e r s e g r o o v e s o n t h e le s s d e v e l o p e d l o n g i t u d i n a l w i n g s , x 2 0


3/9

Seed Morphology in Aconitum 195

Figs. 1-12


4/9

1 9 6 E . M . C A P P E L L E T T I & L . P O L D I ~ :

T h e s e e d f a c e s a r e e i t h e r s m o o t h ( F ig . 1 ) o r r u g u l o s e ( F ig . 1 0) o w i n gt o t h e p r e s e n c e o f r id g e s w h ic h s o m e t im e s e x t e n d i n t o m e m b r a n o u se x p a n s i o n s ( t r a n s v e r s e w i n g s , F i g s . 1 7 - 2 1 ) .

I n t h e f o l l o w i n g a b r i e f d e s c r i p ti o n o f t h e s e e d m o r p h o l o g y o f a ll t a x as t u d i e d is p r e s e n t e d .

1. A c o n i t u m an t h o r a : t h e s e e d s a r e c h a r a c t e r i z e d b y t h e o c c u r r e n c eo f t h r e e l o n g i t u d i n a l w i n g s o f c o m p a r a b l e s i z e o n t h e e d g e s ( F i g . 1 ). T h es e ed fa c es a r e s m o o t h w i t h o n l y o n e r o u n d - t o p p e d t u b e r c le o c c u r r i n g o ne v e r y s in g le r e c t a n g u l a r - s h a p e d e p i d e r m a l c e ll ( F ig s. 2 - 3 ) . S o m e t i m e st h e t u b e r c l e s o c c u r r i n g o n a d j a c e n t c e l l s a r e a l i g n e d ( F i g . 4 ) f o r m i n g at r a n s v e r s a l p a t t e r n ( F ig . 5) . G e n e r a l ly , e p i d e r m a l c ells e x h i b i t w a r t yo r n a m e n t a t i o n s ( F ig . 6), w h i c h a r e m i s s in g o n l y o n t h e c e lls s i t u a t e d o nt h e t o p o f t h e l o n g i t u d i n a l w i n g s r u n n i n g a l o n g th e e d g e s ( F ig . 7) a n d o nt h e p o l y g o n a l - o u t l i n e d c e ll s o f t h e h i l u m r e g i o n ( F i g . 8) .

Q u i t e s i m i la r e p i d e r m a l c e ll m i c r o c h a r a c t e r i s t i c s h a v e b e e n o b s e r v e di n a l l t h e o t h e r A c o n i t u m s p e c i e s a n d s u b s p e c i e s s t u d i e d .

2 . A c o n i t u m n a p el l u s g r o u p : s e e ds w i t h t h r e e l o n g i t u d i n a l w i n gs , o n eo f w h i c h i s d i s t i n c t l y m u c h m o r e d e v e l o p e d t h a n t h e o t h e r t w o ( F ig . 9).

2 .1 . A , n a p e I lu s s u b s p , t a u r i c u m : s e e d f a c e s w i t h r i d g e s m o r e o r l e ssd e v e l o p e d ( d e p e n d i n g o n th e s p e c i m e n ) ( F ig . 1 0) a n d s o m e t i m e s s c a r c e l yi d e n t i f i a b l e t r a n s v e r s e e x p a n s i o n s ( F i g . 11 ).

2 . 2 . A . n a p e l I u s s u b s p , h i a n s : r i dg e s o n t h e s e e d f ac e s e x p a n d e d i n t om o r e o r le ss d e v e l o p e d m e m b r a n o u s t r a n s v e r s e w i n g s ( F ig . 9) . T h e t w ole ss d e v e l o p e d l o n g i t u d i n a l w i n g s s o m e w h a t w a v y ( F i g. 9 ), s o m e t i m e st o u c h e d b y t h e r id g e s, a n d w i t h t r a n s v e r s e g r o o v e s in t h a t c a s e (F i g. 12).

2 .3 . A . n a p e I I u s s u b s p , n e o r n o n t a n u m : n u m e r o u s w e l l m a r k e d r id g e so n t h e s e e d f ac e s w h i c h e x t e n d t o t h e le ss d e v e l o p e d l o n g i t u d i n a l w i n gsa n d g i v e r i se t o t r a n s v e r s e g r o o v e s ( F i g s. 1 3 - 1 4 ) .

Figs . 13-24.--Figs . 13-14. Aconi tum napel lus subsp, neomontanum: m a r k e dridges on the faces and on the less dev elop ed long i tudina l wings . - -F ig . 13. 20;Fig . 14. 40 .--F igs . 15 17. A. var iega tum.- -F ig . 15. seed wi th only onelong i tudina l wing ( left ), 15 .--F ig . 16. large t ransv erse wings on the faceopp osi te to the long i tudina l wing, 12. - -F ig . 17. t ran sve rse wings , 40. - -F ig .18. A. paniculatum: seed wi th on ly one long i tud ina l wing ( r igh t) and t ransve rsewings on the opposi te face, 15.--Fig . 19. A. anguat~folium: v e r y n u m e r o u st ransve rse wings on the face oppos i t e to the long i tud ina l wing , x 30. - -F igs . 2 0-21. A . vuIparia. -- Fig. 20 . wavy appearance o f the long i tud ina l wing , 20 . - -F ig . 21 . t ransve rse m em brano us wings, x 20 . - - F ig . 22 . A . napellu8subsp , tauricum: t r an s v e r s e ex p an s i o n th ro u g h "p i n ch i n g " o f ad j acen tep idermal ce l l s , x 300 . - -Figs . 23-24 . t ransverse expans ions th rough ou twardspro jec t ion o f ad ja cen t ep iderma l ce ll s. - -F ig . 23. A . panicu la tum, 150 . - -F ig .24. A. vulparia, x 150


5/9

Seed M o r p h o lo g y i n Aconitum 197

Fig s. 13 24


6/9

1 9 8 E . M . C A P P E L L E T T I ~ 5 L P O L D I N I :

3 . A c o n i t u m v a r i e g a t u r n g r o u p :3.1. A. var iega tum: only one longitudinal wing present (Fig. 15). Afew (3-4) ridges expanding into large membranous wings (Figs. 16-17).The transverse wings more developed on the face opposite to the edgebearing the longitudinal wing than on the other two faces (Fig. 15).3.2. A . p a n ie u la tu m: only one longitudinal wing. The transversemembranous wings more numerous (5-6) but less expanded than in A.variegatum (Fig. 18).3.3. A. angus t i fo l ium: only one longitudinal wing. Many transverseridges that expand into membranous wings (Fig. 19).

4. A c o n i t u m v u l p a r i a g r o u p :4.1. A. vulparia: very often the longitudinal wing not apparent;when present, the longitudinal wing with a marked wavy appearance(Fig. 20). On all faces the transverse ridges expand into membranouswings (Fig. 21).4.2 . A . lama rcki i : wing pat tern quite comparable to tha t describedfor A. vu lpar ia .

D i s c u s s i o nGreat constancy of seed microcharacteristics has been observedwithin the genus. All the A c o n i tu m species and subspecies studiedexhibit a warty ornamentation of the integument epidermal cells excepton the top of longitudinal wings (when present) and on the hilum region.This kind of ornamentat ion is not an unusual pat tern of epidermal cellsurface, and frequently occurs for instances on trichomes, nor can it beconsidered an exclusive feature of A c o n i tu m seeds, since it has also been

found on seeds of another Ranunculaceous species: Cimici fuga europaeaSCHIPCZ. (CAPPELLETTI,unpubl.).As regards to seed morphology, marked differences have beenobserved within the genus A c o n i t u m . A seed morphological trend hasbeen pointed out, characterized by the reduction of longitudinal wingson the edges with a concomitant development of ridges on the seed facesexpanding into transverse membranous wings. The seed provided withthree equally developed longitudinal wings along the edges and withfaces devoid of ridges (as found in A. anthora), may be regarded as thesimplest type. Another seed type with reduction of two longitudinalwings and appearance of ridges on the faces is apparent in all the

subspecies of A. napel lus studied. The infolding of the less developedlongitudinal wings, never found in the subsp, taur icum, is alreadypresent in the subsp, h ians and even more apparent in the seeds of thesubsp, neomontanum. In a third type, the complete disappearance of twolongitudinal wings is coupled with considerable development of ridges


7/9

Seed Morphology in Aconitum 199expanding into membranous wings (A. variegatum, A. paniculatum, A.angustifolium). The disappearance even of the remaining longitudinalwing along with ridge development on all the faces and edges, gives riseto the seed type of the A. vulparia group (for instance A. vulparia and A.lamarckii). These seed morphological patterns clearly indicate aninverse correlation between the occurrence of longi tudinal wings on theedges and the development of transverse wings and the ir expansion ontothe faces.The overall seed coat morphological pattern of the genus Aconitum isin good agreement both at the infragenerie and infraspeeifie levels withthe current taxonomic scheme (WARNCI(E 1964, GOTZ 1967, SmTZ 1969),thus confirming DAWS & ItEYWOOD'S (1963) st atement about the greatpotential taxonomic value of seed characteristics. The peculiar seedmorphology of A. anthora (the only species with three equally developedlongitudinal wings, smooth faces and cells provided with tubercles)seems to stress its isolated taxonomic position (HEeI 1912).Great significance for understanding the possible origin of thetransverse membranous wings has to be a ttached to the tubercles foundon the seed integument cells ofA. anthora. In fact we can recognize in thealignment of the tubercles of a row of contiguous cells (Figs. 4-5) thebeginnings of the transverse ridges and wings. It is possible to explainthis expansion process through a "pinching" of the middle portion of aseries of adjacent epidermal cells (Fig. 22). In such an instance thetransverse expansions (recognizable only with SEM) can be consideredas an accentuation of a series of aligned tubercles as seen in A. anthora. Asecond possibility by which the transverse expansions ma y originate isthrough an outward projection of a series of adjacent epidermal cells(Figs. 23-24), giving origin to structures easily recognizable even at lowmagnification. In the A. napellus group the first possibility of transverseexpansion is the one most common, while in the other Aconitum groupsoutward projections of a row of cells can be observed. Transverseexpansions according to the first possibility, however, also occur in A.variegatum, A. ioaniculatum and A. angustifoliurn, but only in closeproximity of the edge still bearing the longitudinal wing.

CytologieM studies provide evidence that A. angustifolium is anallopolyploid between a species of the A. variegatum group and A.napellus (most probably subsp, tauricum) (SmTZ 1969). Chemical da taseem to confirm this, since small amounts of aeonitine--the alkaloidcharacterizing all the members of the A. napellu8 group (KaTz &STAE~IELIN 1978)--have been found in A. angustifolium along withmesaeonitine and/or hypaconit ine as main components (KATz &STAEHELIN 1979). On the contrary, the available chemical evidence failsto confirm affinities with the A. variegatum group (KATz & STAEHELIN


8/9

200 E M. CAPPEL LETTI & L POLDINI:

1 97 9, 1 98 0) . S eed m o r p h o lo g y o f A. angustifolium is n o t r e m i n i s c e n t o ft h e A. napellus g r o u p , b u t e x h i b i t s g r e a t r e s e m b l a n c e t o t h e A .variegatum g r o u p . I n A. angustifolium e v e n f u r t h e r m o r p h o l o g i c a lp r o g r e s s i o n w i t h r e s p e c t t o b o t h A. variegatum a n d A. paniculatum ca nb e o b s e r v e d as r e g a r d s th e n u m b e r a n d d e v e l o p m e n t o f t h e m e m b r a n o u st r a n s v e r s e w i n g s, w h i c h e v e n t e n d s t o r e a c h t h e r e m a i n i n g l o n g i t u d i n a lwing .

T h e s i m p l e s e e d m o r p h o l o g y o f A. anthora, a s p ec i e s r eg a r d ed a s ax e r o t h e r m i c r e l i c t (I~EGI 1 9 1 2 ) , s u g g es t s t h a t e co lo g i ca l ad ap t a t i v es i g n i f i c a n c e m a y b e a t t r i b u t e d t o t h e m o r e e l a b o r a t e s e e d c o a t f e a t u r e so c c u r r i n g in t h e o t h e r a c o n i t e s . T h i s h y p o t h e s i s is s u p p o r t e d b y t h e f a c tt h a t w i t h i n t h e A. variegatum a n d A. vulpa~"ia g r o u p s w e fi nd m a r k e d l ym e s o p h i l o u s - h y g r o p h i l o u s n e m o r i c o l e s p e c ie s, w h i le t h e a c o n i t e s o f t h enapellus g r o u p g r o w i n o p e n h a b i t a t s , o f t e n o n r o c k y s o ils , i n d i c a t i v e o fe c o lo g ic a l r e q u i r e m e n t s i n t e r m e d i a t e b e t w e e n A. anthora an d t h e s p ec i e so f t h e A. variegatum a n d t h e A. vulparia g r o u p s . E c o l o g i c a l a d a p t a t i o n sin c o n n e c t i o n w i t h i m p r o v e d f l o a t i n g a b i l i t y w a s s u g g e s t e d f o r t h ee x t e n t o f s e e d t r a n s v e r s e w i n g e x p a n s i o n i n Aconitum (DAMBOLDT &ZrSISfEI~5'~ANN1 97 4) a n d o f n u t l e t t u b e r c u l a t i o n in Limnanthes (HAuPTL~& a l. 1 9 78 ). W e a l s o f eel t h a t t h e t r a n s v e r s e m em b r an o u s s eed w in g s o fAconitum m a y a f f ec t t h e s eed d i sp e r s a l e f f i c i en cy (f l o a t in g ab i l i t y ,h y g r o s c o p i c m o v e m e n t s d i s t a n c i n g o n e s e e d f r o m t h e o t h e r ) a n d m a yp e r h a p s a s su r e o p t i m u m m o i s t u r e c o n d it i on f o r g e r m i n a t io n . O b v i o u s ly ,s u c h a w o r k i n g h y p o t h e s i s n e e d s t o b e e x p e r i m e n t a l l y v e r i f i e d .

R e f e r e n c e s

DAvis, P. H., HEYWOOD,V. H., 1963: Principles of Angiosperm Ta xon om y. --Edinburgh: Oliver.DAMBOLDT,J., ZIMMERMARrN,W., 1974: Aconitum. -- In HEal, G.: I l lustr ierte F lorayon M itteleuropa 3 (3), 152--177 (3ra Ed.) . -- Berlin, Ha mb urg : P. Parey.GOTZ, E. , 1967 : Die Aconitum variegatum-Gruppe und ihre Bastarde in Europa.-- Feddes Repert . 76 (1-2), 1--62.HAUPTLI, H. , WEBSTER, B. D., JalN, S., 1978: V ar ia tio n in nu tl et m or ph ol og y inLimnanthes. -- Ame r. J. Bot. 65 (6), 615--6 24.HEGI, G., 1912: Aconitum. -- In HEGI, G., I l lustr ierte Flora yon M itteleuropa 3(4), 492 --507 (F t Ed.). -- Miinehen: Le hm an n.KATz, A., STAEHELI~, E., 1978 : Diinns ehic htch rom atog raph isehe r Vergleieheiniger europ//iseher Aeo nitarten un d -Hand elsmu ster . -- Pla nta Medica 33(3), 287--288.-- -- 1979: DC -Untersuch ung der europ/iisehen Aconitum napellus-Gruppe. --Pharm. Acta HeN. 54 (9/10), 253--265.-- - - 1980: Fur th er inves t igat ions per ta ining to European Aconi tes . - - P la ntaMediea 39 (3), 209--2 10.SEITZ, W., 1969: Die Ta xo no m ic d er Aconitum napellus-Gruppe in Europa. - -Feddes Reper t . 86 (1) , 1 -7 6.


9/9

Seed Morphology in Aconitum 201STEBBINS~G. L., 1974: Flowering Plants: Evo lut ion Above the Species Level. --Cambridge: Belknap Press.TUTIN, T. G., MERXlVI~LI~ER, H., 1964: Aconitum L. -- In TUTI~ & al.: Flo ra

Europaea l, 211--213. -- Cambridge: University Press.WARNCKE,K., 1964: Die europgischen Sippen der Ac on itum lycoctonum-Gruppe.- Diss. d. Ludwig-Max.-Univ. Miinchen, 1--66.Addre sses of the authors: Prof. E. M. CAPPELLETTI, Istituto di Bot ani ca e

Fisiologia vegetale, Via Orto Bot ani co 15~ 1-35 100 Pa do va , Italy. -- Prof. L.PoLm~TI, Istituto Botani eo, Via A. Valerio 30, L3 41 00 Trieste, Italy.

Documents

Seed Morphology in Some European Aconites (Aconitum,