BALFOUR—-NEW SPECTES OF RHODODENDRON. 317 
thum cited below refers to the relationship and points out the 
diagnostic feature of the indumentum of the leaf under-surface. 
This character is a valuable differential one and easily observed. 
I speak of the indumentum in the Cephalanthum series as 
spongy because of its loose character and it is never blood-red. 
‘In the Fragrans series it is compact and never blood-red. In 
the Anthopogon series it is agglutinated and always blood-red. 
We have to learn a good deal more of these species before a 
comprehensive story of the Cephalanthum series can be written. 
Meanwhile I give the following tentative key of differential 
characters. The material for examination of most of the species 
is not abundant, and may be found hereafter to have been in- 
adequate for a true picture of the species described without, 
however, upsetting the specific determinations. 
KEY TO THE SPECIES. 
1. Under-leaf indumentum spongy é : 2. 
Under-leaf indumentum loose but - hardly 
spongy - 
12. 
2. Perulae persistent . : * : ‘ ‘ 3. 
Perulae deciduous . ; ; : . , 7 
3. Corolla lepidote : d : ‘ ; é 4. 
Corolla elepidote . : i F 6. 
4. Pedicels none. Flowers antibod ‘ i radinum, 
Pedicels 7-8 mm. long lepidote : : : 5. 
5. Stamens hairy. Flowers white ‘ inp idaiiii 
Stamens glabrous. Flowers pale yellow ‘ . Sargentianum. 
6. Leaves 5 cm. long. Bracteoles longer than 
calyx. Flowers cream-coloured ‘ . platyphylium. 
Leaves 4 cm. long. Rratteeles shorter than 
calyx. Flowers white . . cephalanthum. 
7. Corolla hairy outside ; i ‘ ‘ ; 8. 
; Corolla glabrous outside. ; A Q. 
8. Bracteoles shorter than calyx. iftores- 
cence axis elepidote. Flowers white. 
Stamens glabrous cephalanthotdes. 
Bracteoles much longer than calyx. Inflores- 
cence axis oi epg Flowers rose-tinted. : 
Stamens hai ‘ : ; . Sphaeranthum. 
g. Stamens alee 5 : , : , ‘ ro. 
Stamens hairy ; ; ‘ ‘ rr. 
10. Flowers white. Calyx eit at ‘ .  hedyosmum. 
Flowers ae yellow: ganas scale-fim- 
briate : .  praeclarum, 
ea ae axis pepaeaate. Calyx: eciliate : acrarum, 
Inflorescence axis ome Calyx : 
ciliate ; : : P ledoides. 
