‘ F lo r a o f N ew Z e a la n d : ’ o n su c h th e o r e t ic a l q u e s tio n s , h ow ev e r , as th e o r ig in a n d u lt im a t e p e r m
a n en c e o f sp e c ie s, th e y h a v e b e en g r e a tly in flu en c ed b y th e v iew s a n d a rg um en ts o f M r . D a rw in
a n d i l r . W a lla c e ab o v e a llu d e d to , w h ic h in c lin e m e t o regaa-d m o r e fa v o u ra b ly th e h y p o th e s is th a t
it i s t o v a r ia tio n th a t w e m u s t lo o k as th e m e a n s w h ic h N a tu r e h a s a d o p ted for p e o p lin g th e g lo b e
w ith th o s e d iv e r s e e x is t in g fo rm s w h ich , w h en th e y t e n d t o t r a n sm it th e ir ch a ra c te r s u n ch a n g ed
th r o u g h m a n y g en e r a tio n s , are ca lled sp e c ie s . N e v e r th e le s s I m u s t r ep ea t, w h a t I h a v e fu lly sta ted
e ls ew h e r e , th a t th e s e h y p o th e s e s sh o u ld n o t in flu en c e om- t r e a tm e n t o f sp e c ie s, e ith e r a s su b je c ts o f
d e sc r ip tiv e s c ie n c e , o r a s tb e m e a n s o f in v e s tig a tin g tb c p h en om en a o f th e su c c e s s io n o f o rg an ic
fo rm s in tim e , o r th e ir d isp e r sio n a n d r ep la c em en t in area, th o u g h th e y sh o u ld le a d u s t o m o r e
p h ilo so p h ic a l c o n c ep tio n s o n th e s e su b je c ts, an d s t im u la t e u s t o s e ek fo r su c h c om b in a tio n s o f th e ir
chai-acters a s m a y en a b le u s to c la s s iiy tb em b e tte r , an d t o tr a c e th e ir o r ig in b a ck to a n ep o ch
a n te r io r to th a t o f th e ir p r e s e n t ap p earan c e an d co n d itio n . I n d o in g th is , h ow e v e r , th e b e lie v e r in
sp e c ie s b e in g lin e a lly r e la ted fo rm s m u s t em p lo y th e sam e m e th o d s o f in v e s tig a t io n an d fo llow th e
s am e p r in c ip le s th a t g u id e th e b e lie v e r in th e ir b e in g a c tu a l c r ea tio n s, for tb e la tt e r a ssum e s th a t
N a tu r e h a s c r e a ted sp e c ie s jv ith m u tu a l r e la tio n s a n a lo g o u s t o th o s e w h ic h e x is t b e tw e en th e lin e a lly -
d e s c en d ed m em b e r s o f a fam ily , a n d th is is in d e ed th e le a d in g id e a in all n a tu r a l s y s tem s . O n th e
o th e r h a n d , th e r e are so m a n y ch e ck s t o in d is c r im in a te v a r ia tio n , so m a n y in v io la b le law s th a t r e g u la
t e th e p r o d u c tio n o f v a r ie tie s, th e t im e r eq u ir ed t o prod u c e w id e v a r ia tio n s from a n y g iv en spec ific
ty p e is so g r e a t, an d th e n um b e r o f sp e c ie s an d v a r ie tie s k n ow n to p ro p a g a te fo r in d e fin ite p e r iods
a su c c e s s io n o f a b so lu te ly id e n tic a l m em b e r s i s so la r g e , th a t a ll n a tu r a lis ts are a g r e ed th a t for
d e sc r ip tiv e p u rp o se s sp e c ie s m u s t b e t r e a ted as i f th e y w e r e a t tb e ir o r ig in d is tin c t , a n d are d e s tin
e d so to r em a in . H e n c e th e d e s c r ip tiv e n a tu r a lis t w'ho b e lie v e s a ll sp e c ie s to b e d e r iv a tiv e an d
m u ta b le , o n ly d iffe rs in p r a c tic e fr om h im w h o a sse r ts th e con tr a r y , in e x p e c t in g th a t th e p o s te r ity
o f th e o r g a n ism s lie d e sc r ib e s as sp e c ie s m a y , a t som e in d e fin ite ly d is ta n t p e r io d o f tim e , r eq u ir e
I’ed e s c r ip tio n .
I n e ed h a rd ly r em a rk th a t th e c la ssific a to r y b r a n ch o f B o ta n y is th e o n ly o n e from w h ich
th is su b je c t c a n b e ap p ro a ch ed , fo r a g o o d s y s t em m u s t b e fo u n d ed o n a d u e ap p r e c ia tion o f all
th e a t tr ib u t e s o f in d iv id u a l p la n t s ,— u p o n a b a la n c e o f th e ir m o rp h o lo g ic a l, p h y s io lo g ic a l, and
a n a tom ic a l r e la tio n s a t a ll pe r iod s o f th e ir g r ow th . S p e c ie s are c o n v e n tio n a lly a ssum ed t o r ep re s
e n t, w ith a g r e a t am o u n t o f u n ifo rm ity , th e low e s t d e g r e e o f su c h r e la tio n sh ip ; a n d th e fa c ts th a t
in d iv id u a ls are m o r e e a s ily g ro u p ed in to sp e c ie s lim it e d b y ch a ra c te r s, th a n in to v a r ie tie s, or th a n
sp e c ie s are in to lim ita b le g en e r a or g ro u p s o f h ig h e r va lu e , a n d th a t th e r e la tio n sh ip s o f sp e c ie s
are tr a n sm itt e d h e r e d ita r ily in a v e r y em in e n t d eg r e e , are th e s tr o n g e s t ap p earan c es in favour o f
sp e c ie s b e in g o r ig in a l c r e a tio n s , a n d g en e ra , e tc ., a rb itra r ily lim ite d g ro u p s o f th e s e .
T h e d iffe r en c e b e tw e e n v a r ie tie s an d sp e c ie s an d g en e r a in r e sp e c t o f d e fin ab le lim ita t io n is
h ow e v e r o n e o f d e g r e e o n ly , an d i f in c r e a s ed m a te r ia ls an d ob se rv a tio n con firm th e d o c tr in e w h ich
I h a v e for m a n y y e a r s la b o u r ed to e s ta b lish , th a t far m o r e sp e c ie s ar e va r iab le , an d far fewer lim it -
a b le , th a n h a s b e e n su p p o sed , t h a t h y p o th e s is w ill h e p r op o r tion a lly s tr e n g th e n e d w h ich a ssum e s
sp e c ie s to b e a rb itra r ily lim it e d g ro u p s o f v a r ie tie s. W ith th e v iew o f a s c e r ta in in g h ow far m y
ow n exp e r ien c e in c la s sific a tio n w ill h e a r o u t su c h a co n c lu s io n , I sh a ll n ow en d ea v o u r to re -
v iew , w ith o u t r e fe r en c e t o m y p r ev io u s co u c lu s io n s , th e im p r e s s io n s w h ic h 1 h a v e d e r iv ed from
t h e r e tr o sp e c t o f tw e n ty y ea r s' s tu d y o f p la n ts . D u r in g th a t t im e I h a v e cla ssified m a n y la rg e
an d sm a ll F lo r a s , ar c tic , tem p e r a te , an d tr o p ic a l, in su la r an d c o n t in e n t a l: cm b r a cm g ar ea s so
e x te n s iv e and v ar ied a s to ju s t ify , to m y ap p r eh en sion , th e a s sum p tio n th a t th e r e su lts d e r iv ed
from th e s e w o u ld also be app licab le to th e w h o le v e g e ta b le k in g d om . I sh a ll a r ran g e th e s e r e su lts
su c c e s s iv e ly u n d e r th r e e h e a d s ; viz . fa c ts d e r iv ed fr om a s tu d y o f c la s s if ic a t io n ; se c o n d ly , from
d is tr ib u tio n ; th ir d ly , from fo s s ils ; a fte r w h ic h 1 sh a ll e x am in e th e th e o r ie s w ith w h ic h th e s e fa c ts
sh o u ld harm on iz e .
^ 2 .
O n th e G e n e ra l P h en om en a o f V a r ia tio n in th e V eg e ta b le K in g d om .
1. A l l v e g e ta b le fo rm s are m o r e or l e s s p ro n e to va ry a s to th e ir sen s ib le p rop e r tie s, o r (as it
h a s b e en h a p p ily ex p r e ssed in r eg a rd t o a ll o r g a n ism s ) , “ th e y a r c in a s ta t e o f u n s ta b le e q u ilib
r ium .” * N o o rg a n is e x a c t ly s ym m e tr ic a l, n o tw o are e x a c t cou n te rp a r ts, n o tw o in d iv id u a ls are
e x a c t ly a lik e , n o tw o p a r ts o f th e sam e in d iv id u a l e x a c tly c o r r e sp on d , n o tw o sp e c ie s h a v e eq u a l
d iffe ren ce s, an d n o tw o c o u n tr ie s p r e sen t a ll th e v a r ie tie s o f a sp e c ie s c om m o n to b o th , n o r are
th e sp e c ie s o f a n y tw o c o u n tr ie s a lik e in n um b e r an d k in d .
2 . T h e ra te a t w h ich p la n ts va ry is a lw a y s s low , an d th e e x te n t o r d e g r e e o f v a r ia tio n is g r a d
u a ted . S p o r ts e v e n in c o lo u r are com p a ra tiv e ly rar e p h en om en a , an d , a s a g e n e r a l ru le , th e b e s t-
m a rk ed v a r ie tie s ocCur o n th e co n fin e s o f th e g e o g r a p h ic a l area w h ic h a sp e c ie s in h a b its . T h u s th e
sc a r le t M io d o d en d r o n {R . a rb a reum ) o f In d ia in h a b its a ll th e H im a la y a , th e K h a s ia M o u n ta in s , th e
P e n in su la r M o u n ta in s , an d C ey lo u ; an d i t is in th e c e n tr e o f i t s r a n g e (S ik k im a n d th e K h a sia ) th a t
th o s e m e a n fo rm s o c cu r w h ic h b y a g r a d u a ted se r ie s u n ite in to o n e var iab le sp e c ie s th e r o u g h , r u s ty -
lea v ed fo rm o f C e y lo n , an d th e sm o o th , silv e r y -le a v ed fo rm o f th e N o r th -w e s te r n H im a la y a . A
w h ite an d a ro se -c o lo u r ed sp o r t o f ea ch v a r ie ty is fo u n d g r ow in g w ith th e s c a r le t in a ll th e s e lo c a litie
s , h u t e v e ryw h e r e th e s e sp o r ts are few in in d iv id u a ls. A ls o c e r ta in in d iv id u a ls flowe r ea r lie r th an
o th e r s , an d som e o c ca s io n a lly tw ic e a y ea r , I b e lie v e in a ll lo c a litie s .
3 . I find th a t in ev e ry F lo r a a il g ro u p s o f sp e c ie s m a y b e r o u g h ly c la ssified in to th r e e la rg e
d iv is io n s ; o n e in w h ich m o s t sp e c ie s are a p p a r en tly u n v a r y in g ; a n o th e r in w h ich m o s t ar e c o n sp ic u o
u s ly v a r y in g ; an d a th ird w h ic h c o n s is t s o f a m ix tu r e o f b o th in m o r e eq u a l p rop o r tion s. O f
th e s e th e u n v a r y in g sp e c ie s appear so d is t in c t from o n e a n o th e r th a t m o s t b o ta n ists a g r e e a s to th e ir
lim it s , and th e ir o ffspr ing are a t o n c e r e fe rab le b y in sp e c tio n t o th e ir p a r en ts; e a c h p r e s en ts sev e ra l
sp e c ia l ch a ra c te r s, an d i t w o u ld r eq u ir e m a n y in te rm ed ia te fo rm s t o e ffe c t a g ra d u a ted ch a n g e from
a n y o n e to a n o th e r . T h e m o s t v a r y in g sp e c ie s , o n th e c on tra ry , so ru n in to o n e a n o th e r , th a t b o ta n is ts
a r e n o t a g r e ed as to tbeii- lim it s , an d o ften fa il t o r efer th e offsp r in g w ith c e r ta in ty to tb e ir p a r en ts,
e a ch b e in g d is tin g u ish ed from o n e o r m o r e o th e r s b y o n e o r a few su ch tr iflin g ch a ra c te r s, th a t ea ch
g rou p m a y b e r eg a rd ed as a co n tin u o u s se r ie s o f v a r ie tie s, b e tw e e n th e te rm s o f w h ic h n o h ia tu s
e x is ts su g g e s t in g th e in te r c a la tio n o f a n y in t e rm e d ia t e v a r ie ty . T h e g en e r a R u b u s, R o s a , S a lix , and
S a x if r a g a , afford co n sp icu o u s e x am p le s o f th e s e u n s ta b le s p e c ie s ; V e ro n ica , C am p an u la , an d L o b e lia ,
o f com p a ra tiv e ly sta b le o n e s.
4 . O f th e s e n a tu ra l g roups o f v a r y in g an d u n v a r y in g sp e c ie s, som e are la rg e an d som e sm a l l ;
th e y arc a lso v e r y v a r io u sly d is tr ib u ted th r o u g h th e c la sse s, orde rs, an d g en e r a o f th e V e g e ta b le
K in g d om ; b u t , a s a g en e r a l ru le , th e v a r y in g sp e c ie s ar e r e la t iv e ly m o s t n um e r o u s in th o s e c la sse s,
order s, an d g en e r a w h ich are th e s im p le s t in s t r u c tu r e .f C om p le x ity o f s tr u c tu r e i s g en e r a lly ac -
* E ssa y s: Scientific, Political, and Speculative; by Herbert Spencer: p. 280.
t Mr. Darwin, after a verj' laborious analysis of many Floras, finds that the species o f large genera are relatively
more variable than those of sm a ll; a result which I was long disposed to doubt, because of the uumber of variable