SYMMETRY OF THE CENTROSPERM X. 269 
of * interrupted " inflorescences in the Chenopodiacez. Such “fusions” prepare us for 
the notorious fasciation of amarantaceous inflorescences. 
But in other parts of the stem of Chenopodiace where branches shoot out precociously 
similar “ fusions ” take place between branch and main axis or subtending leaf. 
The remaining pages give particulars concerning the various families, genera, and 
species investigated. 
CHENOPODIACEJE. 
The species investigated were Atriplex rosea (two forms), Salsola Kali, and Cheno- 
podium Bonus- Henricus. 
ATRIPLEX ROSEA, (Curves 1-5.) 
The plants were collected on the sea-shore in Anglesey, where there were two 
varieties :— 
(i.) The ordinary prostrate form whose main stem bends over parallel to the surface 
of the soil almost as soon as it emerges from the sand. 
(ii.) An erect form of more slender build, usually found growing on the steeper slopes 
of the sand-hills on the seaward side farther from the sea than the gently sloping or 
level sand where the prostrate form abounds: yet the erect variety was not entirely 
lacking from the latter habitat, so that its difference from the prostrate form is not 
induced by external circumstances. 
Most of my observations concern the more abundant prostrate form, and are of special 
significance because the open flatness of habitat and the prostrate method of growth 
reduce to a minimum differences of the various shoots as regards conditions of light, 
heat, and moisture. 
Before discussing the internode-curves of this species some remarks may be offered 
concerning the phyllotaxis and mode of growth of seedlings and young plants of the 
prostrate form. 
At first the hypogeal development far outstrips the epigeal, and a deep tap-root 
rapidly descends in the sand to the deeper-lying water, while a relatively short shoot is 
being produced (this is demonstrated by a comparison of the second and third columns in 
the following Table, p. 270). The early bending over of the main shoot and the prostrate 
condition of the branches remove the plant largely from the influence of the wind, also 
cause it to take a relatively small part in fixing the sand and to evade the danger of 
early burial. , 
The leaves at the base show a decussate design of phyllotaxis and are opposite or sub- 
Opposite, as are the branches, which very early grow out horizontally, creep over the 
ground, elongate rapidly, and therefore soon equal or exceed in length the main ea 
(see the following Table). The rapid elongation of tlie branches in comparison with the 
stem is associated with the greater lengths of their first internodes, which tend to carry 
the leaves of the branches out of range of those on the main stem or the d cm 
8 
