Cone of Equisetum maximum , Lam. 601 
come to the conclusion that two of these sporangiophores are double in nature 
and represent two concrescent members, while one is a single, unusually 
large, bifascicular sporangiophore. 
The lowest whorl of Cone F of E. maximum , in which the free traces 
are more numerous than in any other whorl examined (fourteen out of 
thirty), shows an extraordinary degree of concresence among the sporangio¬ 
phores. Only one of the free traces supplied a single, monofascicular 
sporangiophore. All the sporangiophores had very short stalks, so that 
their heads tended to be close together, a condition obviously favourable to 
concrescence. The stalks of the sporangiophores are often dilated at their 
insertion on the axis. This, coupled with the unusual shortness of their 
stalks, gives on superficial examination a fallacious impression that the 
sporangiophores are all slightly coherent basally. I have in the following 
paragraphs attempted to analyse the constitution of this whorl. The term 
complex is used throughout to denote a series of sporangiophores showing 
a considerable degree of concrescence. The presence in a complex of 
a given number of mutually independent vascular strands does not 
necessarily indicate that the complex is composed of a number of members 
equal to the strands. Bifascicular sporangiophores, single in nature, i. e. 
sporangiophores whose traces divide while still in the cortex, are common 
in E. maximum , and as such sporangiophores tend to be rather large 
they are inclined to be more closely approximated to their neighbours 
and more frequently fused with them. Thus bifascicular members are 
relatively common in complexes. On the other hand, there seems to 
be at least one possible case in which a more or less reduced or arrested 
member of a complex was devoid of a vascular strand (cf. under 10 of 
analysis). These two considerations introduce an element of difficulty, even 
of uncertainty, in analysing complexes. In the following section, however, 
I have indicated the only two cases in which I felt any doubt as to the 
number of constituents in a complex. 
Analysis of the Lowest Whorl of Cone F of E. maximum. 
1. A complex of four sporangiophores. This is supplied by a normal 
trace, two free traces, and another normal trace. This complex is locally 
concrescent (over the middle region of the stalk and part of the head) with: 
2 . A single, monofascicular sporangiophore. This sporangiophore is 
followed by: 
3. A complex of two sporangiophores. The first and largest member 
contains two closely approximated vascular strands, one a free strand and 
the other showing the B anomaly. The second sporangiophore of the com¬ 
plex contains a free strand. This complex is followed by : 
4. A complex of three sporangiophores. The first member possesses 
