XXIV ELOKA OE NEW ZEALAND.
r e tir em e n t o f tlie p la n ts to th e s um m it o f th e N ew Z e a lan d m o im ta in s* ^ Avould b e th e n e c e ssa ry
consequenc e o f th e am elio i'a tio n o f c lim a te th a t folloAved th e iso la tio n o f N cav Ze a lan d , a n d th e
re p la c em en t o f th e A n ta rc tic c o n tin e n t b y th e p re s e n t ocean.
T h e c lim a te tlm o n g h o n t th e so u th tem p e ra te zone is so eq u ab le, a n d th e iso th e rm a l lin e s ai’e so
p a ra lle l to th o s e o f la titu d e , th a t i t is n o t ea sy for th e N ew Z e a lan d n a tu i’a lis t to re a liz e th e a lte re d
c ircum s tan c e s th a t would re n d e r th e p la in s o f h is is la n d su ita b le for th e g row th o f p la n ts th a t now
in h a b it its m o u n ta in s o n ly f ; b u t i f h e g la n c e a t th e m a p o f tlie iso th e rm a l lin e s o f th e n o r th e rn
h em isp h e re , h e Avill see hoAV A'ai’ie d a re th e c lim a te s o f reg io n s in th e same la titu d e ; th a t L o u d o n , Avith
a m e an tem p e ra tu re o f 51°, is in th e sam e la titu d e as H u d so n ’s B ay , AAdiere th e m e an tem p e ra tu re is
30°, a n d th e soil CA^er fro z en : an d h e Avill fu r th e r b e ab le to u n d e rs ta n d b y a little reflectio n , how a
ch a n g e in th e re la tiv e p o s itio n s o f sea an d la n d would, by iso la tin g L a b ra d o r, ra ise its tem p e ra tu re
1 0 °-1 5 °, c a u sin g th e d e s tru c tio n o f all th e n a tiv e p la n ts th a t d id n o t r e tir e to its m o u n ta in -to p s , an d
fav o u rin g th e im m ig ra tio n o f th e species o f a m o re g en ia l c lim a te .
T h e fii’st in fe ren c e from su ch a n h y p o th e sis is th a t th e A lp in e p la n ts o f N ew Z e a lan d , h av in g
sm'vived th e g re a te s t ch an g e s, a re its m o s t a n c ie n t co lo n ists ; an d i t is a m o s t im p o r ta n t o n e in m a n y
re sp e c ts, b u t especially Avhen co n sid e red AAuth re fe re n c e to th e m o u n ta in floras o f th e Pacific an d
s o u th e rn h em isp h e re g en e ra lly . T h e se m a y b e classed u n d e r th r e e h e a d s ! ^—
1. T h o se th a t c o n ta in id e n tic a l o r representatiA^e species o f th e A n ta i’c tic F lo ra , an d n o n e th a t
a re p e c u lia rly A r c ti c ; as th e T a sm a n ia n a n d N ew Z e a lan d A lp s§ .
2. T h o se th a t c o n ta in , b esid e s th e se , p e c u lia ritie s o f th e N o r th e rn a n d A rc tic F lo ra s || ; as th e
S o u th A m e ric a n Alps.
3. T h o se th a t co n ta in th e peculiai’itie s o f n e i th e r ; as th e m o u n ta in s o f S o u th Afr’ic a an d th e
P acific I s la n d s .
* With regard to the British mountains, Professor Forbes imagines that they Avere islets iu the glacial ocean,
and received their plants by transportation of seeds with soil, on ice from the Arctic regions. This appears to me
to Avant support, and there is much in the distribution of Arctic plants especially, wholly opposed to the idea of ice
transport being an active agent in dispersion. A lowering of 10° of mean temperature would render the greater
part of Britain suitable to the growth of Arctic plants ; it would give it the climate of Labrador, situated in the
same latitude on the opposite side of the Atlantic. Britain is the warmest spot in its latitude, and a very slight
geological change would lower its mean temperature many degi’ees.
t The New Zealand naturalist has probably a very simple means of determining for himself whether his island
has been subject to a geologically recent amelioration of climate ; to do which, let him examine the flord-like bays of
the Avest coast of the Middle Island, for evidence of the glaciers which there exist in the mountains having formerly
descended loAver than they now do. Glaciers to this day descend to the level of the sea in South Chili, at the
latitude of Dusky Bay ; and if they have done so in the latter locality, they Avill have left memorials, in the shape of
boulders, moraines, and scratched and polished rocks.
! I need scarcely remind my reader that in thus sketching the characteristics of these Alpine floras, I make
no <allusion to exceptions that do not alter the main features. I am far from asserting that there are no pccidiar
Arctic or Antarctic forms in the Pacific Islands, nor any peculiarly Arctic ones in Tasmania and New Zealand : but
if, on the one hand, future discoveries of such shall weaken the points of difference between these three mountain
regions, on the other they might be very much strengthened by adducing the number of Arctic species coramou
to tbe South American Alps, but not found in the others.
§ These Antarctic forms are very numerous ; famihar ones are Actxna, Drapeles, Donatia, Gunnera, Oreoinyr-
rhis, Lagenophora, Forstera, Ourisia, Fagus, Callixene, Astelia, Gaimardia, Alepynm, Oreoholua, Carpha, Uncinia.
II Berberia, Slsynihrium, T/daspi, Arabia, Braha, Sagina, Lychnis, Cerasiium, Fragaria, Lathyrus, Vicia, Hip-
puris, Chrysosplenium, Ribes, Saxifraga, Valeriana, Aster, Hieracium, Stachys, Prbnula, Anayallis, Pingiiicula,
Statice, Empetrum, Phleum, Flymus, Ilordeum.
AVc th u s o b serv e th a t th e w a n t o f a n A rc tic o r A n ta r c tic F lo r a a t all in th e P a c ific is la n d s,
an d th e p re s en c e o f a n A rc tic o n e in th e A m e ric an A lp s , a re th e p rom in e n t f e a tu r e s ; a n d I sh a ll
confine m y rem a rk s u p o n th e s e to th e fa c t th a t, Avith re g a rd to th e iso la te d is la n d s o f th e Pacific,
th e y a rc s itu a te d in to o Avarm a la titu d e to h av e h a d th e ir tem p e r a tu r e cooled b y c h a n g e s in th e r e l a tiv
e p o sitio n o f la n d a n d oce an, so as to h av e h a rb o u re d an A n ta r c tic v eg e ta tio n . AA'ith re g a rd to th e
S o u th A m e ric a n A lp s , th e r e is d ire c t la n d com m u n ic a tio n alo n g th e A n d e s from A rc tic to A n ta r c tic
r e g io n s ; b y Avhich n o t o n ly m a y th e s tr ic tly A r c tic g e n e ra a n d species h av e m ig ra te d to C ap e H o rn ,
b u t b y w h ich m a n y A n ta r c tic o n e s m a y haA^e ad v an c ed nortliAvard to th e e q u a to r* .
T h e re is s till a n o th e r p o in t in co n n e c tio n w itli th e su b je c t o f th e re la tiv e a n tiq u ity o f p la n ts , a n d
in ad d u c in g i t I m u s t ag a in re fe r to th e ' P rin c ip le s o f G eo lo g y ,’ Avhere i t is said, " A s a g e n e ra l ru le ,
species com mo n to m a n y d is ta n t proAunces, o r th o s e n ow fo u n d to in h a b it m a n y d is ta n t p a r ts o f th e
globe, a re to b e re g a rd e d as th e m o s t a n c ie n t . . . . th e ir Avide diflPusion shoAvs th a t th e y h av e
h a d a lo n g tim e to sp re ad th em se lv e s, a n d h a v e b e e n ab le to surAuve m a n y im p o r ta n t ch a n g e s in
P h y sic a l G c o g ra p h y f.” I f th is b e tru e , i t folloAvs th a t, co n s is te n tly Avith th e th e o ry o f th e a n tiq u ity
o f th e A lp in e flo ra o f Ncav Z e a lan d , we sh o u ld fin d am o n g s t th e p la n ts com m o n to N ew Z e a lan d an d
th e A n ta i’c tic is la n d s, som e o f th e m o s t c o sm o p o lita n ; a n d Ave do so in M o n tia fo n ta n a , Ca llitrich e
ve rn a , C ardamine h ir su ta , E p ilo h ium te tra g o n um, a n d m a n y o th e rs.
O n the other hand, it must be recollected that there are other causes besides antiquity and
facility for migration, that determine the distribution of plants; these are their poAA’er, mentioned
above, of invading and effecting a settlement in a country preoccupied with its own species, and their
adaptability to A'arious climates: AAith regard to the first of these points, it is of more importance
than is generally assumed, and I have alluded to its effects under S o n ch u s, in the body of this w o rk .
A s regards climates, the plants mentioned above seem wonderfully indifferent to its effects!.
Again, even though we may safely pronounce most species of ubiquitous plants to liave outlived
many geological changes, Ave may not reverse the position, and assume local species to be amongst the
most recently created; for Avhether (as has been conjectured) species, like indiAuduals, die out in the
course o f time, ioUoAAung some inscrutable law whose operations we have not yet traced, or whether
(as in some instances Ave knoAv to be the case) they are destroyed by natural causes (geological or
others), they must in either case become scarce and local Avhile they are in process of disappearance.
I n th e above sp ecu lativ e review o f some o f th e cau ses w h ich a p p e a r to affect th e life a n d ra n g e
o f species in th e v eg e tab le k in g d om , I h av e n o t to u c h e d u p o n o n e p o in t, n am e ly , th a t w h ic h co n c e rn s
th e o rig in a l in tro d u c tio n o f ex istin g species o f p la n ts u p o n th e e a rth . I h av e as sum ed th a t th e y h av e
ex isted fo r ages in th e fo rms th e y noAV r e ta in , th a t a s sum p tio n ag re e in g , in m y o p in io n , w ith th e facts
e licited h y a su rv ey o f aU th e p h en om en a th e y p re s e n t, an d , a c co rd in g to th e m o s t em in e n t zoolo-
* Why these Antarctic forms have not extended into North America, as the Ai’ctic ones have into South America,
IS a curious problem, and the only hypothesis that suggests itself is derived from the fact that though the Panama
Andes are not now sufficiently lofty for the transit of either, there is nothing to contradict the supposition that they
may have had suificient altitude at a former period, and that one Avhich preceded the advance of the Antarctic species
to so high a nortliern latitude.
t Principles of Geology, ed. 9. p. 703.
! Mr. Watson (Cybele Britmunca) gives the range of Callitriche in Britain alone as including mean temperatures
of 40° to 53°, and as ascending from the level of the sea to nearly 3000 feet in the Ea st Highlands of
Scotland. Montia, according to the same authority, enjoys a range of 36° to 53°, and ascends to 3300 f e e t; Epilo-
bium, a temperature of 40° to 51°, and ascends to 2000 feet; Cardamine, a temperature of 37° to 52°, aiuKascends
to 3000 feet.