194 
THIRTEENTH REPORT. 
the aerial stalk of the young plant and its roots die, and thus completely 
sever the connection between the young parent plant and the earth- 
branch. The latter being left perfectly independent, lies dormant until 
the following spring when the terminal bud grows upward into the aerial 
stalk of the season, at which time the earth-branch ceases to be such, 
but develops its rootlets of last year's formation into large roots, and 
functions itself as such, changing from a succulent to a hard woody 
texture. 
After the aerial stalk is established it sends forward new earth- 
branches as did the parent seedling of the previous year, and in the 
prolongation of last year’s growth. These earth-branches branch more 
or less, each branch diverging somewhat, but tending to grow parallel 
with the main branch of the last year’s growth. At the end of the sea- 
son the aerial stalk and its roots all die as did the seedling plant the 
year before, thus completely severing all living connections with the 
new earth-branches, which are left independent to repeat the process 
just described the next year and on indefinitely. This is the life history 
of a' single plant. 
It must now be evident why I have designated this group of sunflow- 
ers as migratorial. It is by this character that they spread by under- 
ground growth. It will be seen from the foregoing that an earth-branch 
has two seasons duration, less than a year and a half in all ; or from the 
first of May until the last of October of the next year is the term of 
their life. This is the reason why I have said that they are not per- 
ennial or properly biennial. The first season of their existence I have 
designated as their formative season, during which they perform no 
other work than that of growth and preparation for the second or 
functional season, during which they produce from their terminal buds 
the aerial stalks of that season and the earth-branch for the following 
vear’s work. 
Each year’s plants leave behind them lines of dead annual ancestors, 
each one of which was produced vegetatively by its annual parent of the 
previous year. Each plant lives a sort of double life, while dying from 
age and exhaustion, they are renewing their youth by producing from 
their own bodies a young plant in the shape of an earth-branch which 
will function next year and die. The old plant and the new, parent and 
offspring, age and youth, death and revival are all in one plant at one 
time. 
Having shown very marked differences between the rootstock proper 
and the so-called rootstock of the migratorial sunflowers. I will now 
return to and proceed with the extended description of each of the great 
perennial divisions of the genus under consideration. 
The group which I have described as stationary is such for the reason 
that each plant has a perennial crown which annually produces buds 
just at the surface of the earth and around the present year’s stem which 
dies down to the ground each autumn. The succeeding spring these 
buds grow and become the aerial stalks and stems of that season. Hith- 
erto botanists have described these plants as being perennial by “thick- 
ened fleshy roots and creeping rootstocks.” I will here repeat that they 
have no rootstocks or anything corresponding to them. Unlike the mi- 
gratorial plants they have nothing underground but roots. By means 
of the roots this section of the sunflowers is divisible into two diverse 
