h 5 .
On th e T r o p ic a l A u s tr a lia n Flo ra .
T h e r e ar e n o g e o g r a p h ic a l o r o th e r fe a tu r e s o f th e A u str a lia n c o n t in e n t w h ic h en a b le m e to
draw a n y n a tu r a l b o u n d a ry b e tw e en tem p e r a te an d tr o p ic a l A u s tr a lia . I u s e le c t in g a b o ta n ic a l tr o p ic
o f C apr icorn, I h e n c e h a v e h ad r e co u r se to th e d istr ih u tio n o f th e p la n ts th em s e lv e s , au d th e s e m u s t
afford v e iy v a g u e data. T h e tro p ica l F lo r a , iu o n e fo rm , ad v an c e s fu r th e r so u th o n th e w e s t c o a st
a n d o n th e c en tr a l m e r id ia n th a n o n th e e a s t, b e ca u se o f th e a b sen c e o f m o u n ta in s , an d h e n c e o f
w a te r , o n th e w e st, w h ich cau se s c om b in e t o favom- th e p r ev a len c e o f h o t, d e s e r t ty p e s o f v e g e ta tio n ,
m a n y o f w h ich ad v a n c e ev en to Sw a n R iv e r . O n th e e a s t c o a s t a g a in th e c lim a te is m o istc r , an d we
h e n c e n o t o n ly fin d th e m o s t m a rk ed fe a tu r e s o f e x tra trop ica l A u s t r a lia n v e g e ta tio n ,— S ta c k h o u s ia ,
B o r o n ia , T e tr a th e c a , Com e sp e rm a , v a r io u s g en e r a o f E p a c r id eæ , L eg um in o soe , M y r ta c eæ , e t c ., ad v
a n c in g in fu ll fo r c e as far n o r th as M o r e to n B a y , la t . 2 7 ° , w h ich I h a v e som ew h a t a rb itrar ily
a ssum ed th e r e t o b e th e lim it o f th e tem p e r a te F lo r a ,— h u t P a lm s and o th e r t r o p ic a l fo rm s r u n n
in g d ow n th e c o a s t a lm o st t o B a s s ’s S tr a its . T o th e n o r thw a rd o f M o r e to n B a y (ju d g in g e sp e c ia lly
from M r . B id w ill’s TVide B a y c o lle c tio n s ) n o t o n ly d o m a n y tem p e r a te fo rm s disappear, b u t tro p ica l
o n e s ,— M a lv a c eæ , S te r cu lia c eæ , A c a n th a c eæ , E u ph o rh ia c eoe , C onvolvulaceæ, M e lia c eæ , and S a p in -
da c eæ . F icu s, to g e th e r w ith n um e r o u s tr o p ic a l In d ia n w e ed s ,— b e c om e a p r e v a ilin g fea tu r e in th e
lan d scap e . T h e A ra u ca r ia s, a c c o rd in g to M 'G illivT a y (V o y . R a ttle sn a k e , 1 8 4 6 - 5 0 ) , b e g in a t P o r t
B ow e n a n d ad v an c e to Cape M e lv ille . P a n d a n u s , a c co rd in g to th e sam e a u th o r ity , c om m en c e s a t
M o r e to n Is la n d .
O n th e w e s t co a s t I am p u z z led w h e r e t o draw th e lin e . J u d g iu g from D rum m o u d ’s h e r b
a r ium , fo rm ed b e tw e en th e M o o r e a n d M u r ch iso n r iv er s (lat. 2 7 ° 3 0 ' S .) , th e v e g e ta t io n is th e r e s till
ty p ic a lly th a t o f th e Sw a n R iv e r , th o u g h m u c h m od ified , an d r ed u c ed g r e a tly in n um b e r o f g en e ra
a n d sp e c ie s. S ir G. G r ey , in h is a d v en tu rou s jo u r n e y fr om P o r t R e g e n t to Sw a n R iv e r , en um e r a te s
v a r io u s em in e n tly tr o p ic a l fo rm s as o c cu r r in g t o th e n o r th o f S h a rk s B a y (lat. 2 6 ° S .) , a s N u tm e g ,*
A r a u c a r i a * C a lam u s (ab u n d a n t). V in e s , m a n y F ig s , an d A r e c a , to g e th e r w ith a B a n k s ia o f Sw an R iv e r ,
w h ic h h e d is tin c t ly a llu d e s t o a s b e in g q u ite ex c ep tio n a l (p. 2 4 7 ) . T o th e so u thw a rd o f S h a rk s B a y
a g a in , h e m e t w ith X a n th o r rh c e a a n d S o w - th is t le ,t b o th o f w h o s e n o r th e rn lim it s h e g iv e s a s 2 8 ° S .,
a n d Z am ia (la t. 2 9 ° S .) . T h e p a ra lle l o f S h a r k s B a y , I h a v e h e n c e a ssum ed to b e n o r th o f t h e p o s it
io n o f t h e tr o p ic o f v e g e ta tio n .
I n d e te rm in in g w h a t m a y b e ca lled th e tr o p ic o f v e g e ta tio n , reg a rd m u s t b e h a d n o t o n ly to th e
la t itu d e a u d iso th e rm a l lin e s , b u t t o th e a b u u d au c e o f th e v e g e ta tio n an d it s ch a ra c ter : an d , in d e ed ,
in su c h a c o u n tr y a s A u s tr a lia th e la t te r e lem e n t s are perhaps o f th e g r e a te st im p o r ta n c e , ow'ing to
th e d im in u t io n n o r thw a rd o f so m a n y pe cu lia r g en e r a th a t m a k e u p a la r g e prop o rtion o f th e
ex tr a -tr o p ic a l v e g e ta t io n , and t o th e fa c t th a t th e t r o p ic a l F lo ra is so v e ry p o o r in n um b e r o f sp e c ie s,
an d d e fic ien t in su c h co n sp icu o u s ly tro p ica l g en e r a a s E p ip h y tic O r ch id s, P a lm s , F e rn s , S c itam in eæ ,
e tc . e tc .
T a k in g a ll e lem e n ts in to co n s id e r a tio n , o f th e v e g e ta tio n , a c tu a l tem p e ra tu r e , and r e la tiv e h u *
1 find no notice elsewhere of these genera being found on the west coast, and suspect some error.
f Leichardt mentions the Sow-thistle as abundant in lat. 2.5° 30' S. on the Gilbert range.
m id ity , w e m a y a ssum e th a t th e tr o p ic a l an d t em p e r a te A u s tr a lia n F lo r a s b le n d o n b o th (ea st aud
w e st) m e r id ia n s a t b e tw e e n la t . 2 6 ° an d 2 9 ° S. ; a n d h a d we c om p le te F lo r a s o f t h e in c lu d ed para lle ls
o f la t itu d e , i t w o u ld n o t b e d ifficu lt t o d e te rm in e b y th e a ffin itie s o f th e p e cu lia r (en d em ic ) sp e c ie s, and
th e d is t r ib u tio n o f th o s e th a t e x t e n d e ith e r n o r th or s o u th o f th o s e p a ra lle ls, w h ic h t o re fe r to th e t r o pica
l F lo r a an d w h ic h to th e tem p e r a te .
W ith r egard t o th e a c tu a l tem p e r a tu r e o f th e A u s tr a lia n tr o p ic a l v e g e ta tio n , it ap p ro x im a te s to
th e iso th e rm a l o f 6 8 °.
T h e g en e r a l b o ta n ic a l fea tu r e s o f th e t r o p ic a l v e g e ta tio n m a y b e g a th e r ed from th e e x c e lle n t
nar ra tiv e s o f L e ich a rd t, M it c h e ll, M 'G illiv r a y , Carrón, an d e sp e c ia lly o f M u e lle r , for th e in te r io r ,
an d o f B r ow n , C u n n in g h am , an d M 'G illiv r a y for th e c o a sts. T h e m o s t p r om in en t fea tu r e i s th e
rai’it y o f C ry p to g am s, w h ic h are a lm o s t w h o lly a b s en t in w e s te r n an d c e n tr a l tr o p ic a l A u s tr a lia ,
an d in th e is la n d s o f th e G u lf o f Carpentar ia, b u t ar e m o r e a b u n d a n t (e sp e c ia lly th e F e rn s) on
th e norfch-east c o a st. T h e a b sen c e o f B am b o o s is a n o th e r v e r y str ik in g fea tu r e , th o u g h th e s e are
said to ab ou n d iu A rn h e im ’s L a n d (MueUer, L in n . J o u rn . B o t . ii. p. 1 3 8 ) . E p ip h y tic O r ch id s are
a lso v e r y rare. E u c a ly p ti an d A c a c iæ fo rm th e m a ss o f t h e arb o r eou s an d sh ru b b y v e g e ta t io n h e r e as
e lsew h e r e th r o u g h o u t A u s tr a lia , n e x t to w h ich som e o f th e m o s t c om m o n an d n o tic e a b le arbor eous
fea tu r e s o f v e g e ta t io n are afforded b y clum p s o f P a n d a n i (o n e sp e c ie s in d ic a tin g fr e sh -w a te r in th e
in te r io r ), B r a c h y c h ito n , A d a n s o n ia , o n th e n o r th -w e s t q u arter , a n d Coch losperm um , an d m a n y o th e r
g en e r a o n th e n o r th -e a s t. C a su a r in a , C a llitr is , a n d o th e r la r g e tr e e s s e em t o b e rar e th o u g h n o t
w h o lly w a n tin g o n th e w e st co a st.
T b e prin c ip a l tr o p ic a l p h a se s o f v e g e ta tio n d esc r ib ed b y M u e lle r are,—
1. T h e v a r ied arbor eous an d sh ru b b y c lo th in g o f th e e a ste rn s lo p e s o f th e e a ste rn ra n g e s, wh e r e
n um e ro u s In d ia n g en e r a o f um b ra g eo u s tr e e s are in te r sp e r sed w ith A u s tr a lia n ; th is , ca lled th e
“ B ru shw o o d ,” or “ Cedar ” c o u n tr y , fu r th e r co n ta in s th e m o s t n um e r o u s r ep r e sen ta tiv e s o f th e
P o ly n e s ia n an d M a la y a n F lo r a s ; to g e th e r w ith C y c a s th ir ty f e e t h ig h , an d va r iou s P a lm s o f th e
g en e r a Ca lam u s, A r e c a , C a r y o ta , a n d L iv is to n a .
2 . T h e “ B r ig a low S c r u b ” e x ten d s o v e r th e e lev a ted sa n d s to n e p la in s w e s t o f th e c o a s t r a n g e in
ea st A u str a lia , a s far a s th e N ew c a s t le r a n g e (lat. 1 8 ° -2 0 ° ) . T h is i s a lso a v e ry vai-ied v e g e ta tio n ,
ch ie fly o f sm a ll tr e e s an d sh ru b s o f C a p p a r id e a , P itto s p o r eæ , B a u h in ia , S te r cu lia c eæ , e tc . H e r e
D e la b e ch ia an d B ra c h y c h ito n , form a r em a rk a b le se co n d a ry fea tu r e ; d is tin g u ish e d as th e B o tt le - tr e e
Scru b , fr om th e ir tum id t r a n k s . T h is v e g e ta tio n i s e ls ew h e r e * d esc r ib ed b y M u e lle r a s e x te n d in g
from th e B u v d ck iii t o th e U p p e r D a r lin g river s, a n d c e a s in g tow a rd s th e so u th -w e s t, som ew h e r e near
M o u n t S e r le , M o u n t M u r ch iso n , or Cooper ’s river.
3 . O p en d ow n s o f b a sa lt, n e a r ly d e s titu te o f tr e e s, e x c e p t a lo n g wate r cou r se s. T h e v e g e ta tio n
is ch ie fly h e rb a c eou s, an d m u c h o f i t a n n u a l ; th e s o il is r ich , au d a fte r th e ra in s p rod u c e s a lu x u r ia n t
crop o f e x c e lle n t gi-ass a n d h e rb a c eou s p la n t s .f
4 . T h e d e se r t p r e sen ts v a r io u s a ssem b la g e s o f p la n ts a c c o rd in g a s th e s o il is sa lin e , c la y e y , or
sa n d y , b u t th e s e p la n ts a r e a lm o st th e sam e a s th o s e o f e x tra trop ica l A u str a lia , w ith th e e x c e p tio n o f
var ious sp e c ie s o f P o r tid a c eæ ,. S o lan um , E u p h o i'b ia , C a ssia , Gomphi'ena, P tilo tu s , T r ia n th em a , A ijl-
m e r ia , an d o th e r P a ro n y ch ieæ .
* Report on Plants ofBabbage’a Expedition, (Victoria, 1868).
t îlu e ller remarks that a Verbena forms so conspicuous a feature over large tracts of country as to have suggested
the name o f Vervain Plains ; it is very singular that tids should be the South American V. BonariensU, and
I should think an introduced plant.