Sterile Varieties. 91 
are destitute of flowers; and the thin, transparent bracts 
are transformed into small green leaves. The variety 
is much cultivated in gardens, partly as a curiosity and 
partly because their green "flowers" do not wither but 
remain fresh on the plant ; which renders it of a decora- 
tive effect until far into the autumn. 1 The variety arose 
in a crop of seedlings about the middle of the last cen- 
tury in Boskoop in Holland, and since then has been 
grown from tubers. It occasionally bears isolated red 
ray florets but, so far as I know, never sets seed. 
Some years ago I obtained what seems to be a new 
and hitherto undescribed form of green Dahlia through 
the kindness of Messrs. ZOCHER & Co. in Haarlem. It 
is not known whence this form came because it was at 
first taken for the type of green Dahlia we have just 
been considering. It differs from this however in the 
fact that the green heads are not of the normal form 
and size but transformed into long green leaf -bearing 
spikes like that figured in Fig. 14 with the exception of 
the clump at the top. 
This form produced elongated flowers of this kind in 
great numbers in the nursery garden ; but it could never, 
so to speak, bring its growth to a conclusion. They grow 
until the autumn and often longer, and frequently attain 
a length of 30 centimeters and more. They behaved in 
exactly the same way in my garden until last year when 
I manured them heavily. Then there appeared from a 
few of the green "flowers" in late autumn a little head 
at the uppermost end (Fig. 14). This unfolded, but 
consisted of green bracts only; it contained neither flow- 
ers nor seeds. The plant is therefore perfectly sterile. 
Another variety closely analogous with this is the 
1 See the literature in PENZIG'S Teratologic, IT, p. 71. 
