Index . 
xii 
Figures. 
page 
20. P. officinalis. Petiole, showing well-developed medullary system of 
bundles. Bundles of adaxial portion of vascular ring at avr 
(Worsdell) - 445 
21. Rudbeckia laciniata. Vascular cylinder of stem, showing absence ot 
medullary strands (Worsdell) 445 
22. R. maxima. Ditto, showing presence of medullary bundles ( mb ) 
(Worsdell) 445 
23. R. maxima. Leaf, showing complete absence of medullary bundles 
(Worsdell) 445 
24. Echinacea (Rudbeckia) purpurea. Vascular cylinder of stem, showing 
rudimentary central medullary bundles ( mb ) (Worsdell) . . 445 
25. E. (Rudbeckia) purpurea. Petiole, showing medullary bundles (mb). 
The most peripheral of these (pmb) are recent lateral derivatives 
from the arc-bundles to which they are opposed (Worsdell) . 446 
26. Inula Helenium. Segment of vascular ring of stem, showing medullary 
phloem-strands (nips). Leaf-bundles at lb (Worsdell) . . 448 
27. I. Helenium. Petiole, showing well-marked scattered disposition of 
the bundles, and the small inverted bundles ( pms ) on the ventral 
side of the median bundle of the arc (Worsdell) .... 448 
1-5. Transverse sections of leaf-bundles (Agnes Arber) .... 461 
6. Carludovica rotundifolius H. Wendl. Transverse section of bundle 
from near growing point of axis (Agnes Arber) .... 463 
7. Sciaphila purpurea Benth. Transverse section of a bundle from an 
axis less than 1 mm. in diameter (Agnes Arber) . . . 463 
1. Rhizoclonium hieroglyphicum, (Klitz.) Stockm. a, transverse section 
of a filament in the autumn condition ; B, external view of part of 
a similar filament ; C and D, transverse sections of a very narrow 
form ; e and F, transverse sections of a much larger form ; g, part 
of a longitudinal section of a similar filament (Carter) . , 470 
2. Chaetomorpha, Kiitz. A and B, Ch. gracilis, Kiitz. Transverse sections. 
C, Ch. Linum, (Muell.) Kiitz. Longitudinal section (Carter) . 471 
Map of New Zealand and outlying islands (Willis) .... 479 
1. Four-leaved sterile plant showing current tuber buried about 18 mm. 
New tuber formed on short stalk at shallower depth (Oct. 1917) 
(Osborn) 486 
2. Two-leaved sterile plant with current tuber 4 mm. below ground-level. 
New r tuber formed on long stalk. Sunken about 11 mm. (Oct. 1917) 
(Osborn) '486 
3. Single-leaved plant with current tuber partially exposed. New tuber 
as yet scarcely swollen, but sunken to 7 mm. (Sept. 14,1918) (Osborn) 486 
4. Graph showing variation in depth of current and new tubers on 186 
plants collected from (approx.) 300 sq. cm. soil (Oct. 1917) 
(Osborn) 488 
5. Single-leaved plant with current tuber C.T. and two old season’s coats, 
o.T.j and o.t. 2 . This plant is entering on the fourth season of 
growth. At this date the root is short and no new tuber visible 
(June 13, 1918) (Osborn) 490 
6. Two-leaved plant with current tuber c.T. at 1 1 mm. depth, new tuber 
N.T. just forming. Coats of three previous seasons’ tubers (o.t.j, 
o.t. 2s 0.t. 3 ) are just below ground-level, showing depth adjustment 
in 1917 (July 11, 1918) (Osborn) 490 
7. Three-leaved plant with current tuber C.T. at 9 mm. depth. Old 
tuber coats (o.T., &c.) of four previous seasons at shallower depth 
(July li, 1918) (Osborn) 490 
8-14. Regenerating leaves collected in field (Oct. 1917)* 8* Detached leai 
lying horizontally on soil showing regeneration. A stalk’s minute 
