Inflorescence - peduncle

[Guido Mathieu]

Hi Felipe,

> Part of your confusion is perhaps due to the inaccurate definitions for
inflorescence and stem that we adopted in POC.

Actually not. It is due to the consideration that definitions solely based on
'agreement' will stand as long as people are 'willing' to agree.

> 1. Stem: the axial system of plants which is usually above ground and more or
less negatively geotropic, bears leaves and buds, is exogenous in origin, often
indeterminate in growth and with secondary thickening.
> 2. Inflorescence: That part of the axial system of plants that bears flowers.
> 3. Peduncle: the stalk of an inflorescence; that part of the inflorescence
below the first flower or inflorescence branch and above the last foliage leaf.
> Therefore, peduncle is part of inflorescence.

Based on the definitions you provided (thanks!) one might reason even so: 

1. The stem is the axial system of plants
2. The inflorescence is that part of the axial system that bears flowers
3. The peduncle doesn't bear flowers ('below the first flower')
Therefore the peduncle is not part of the inflorescence.

Don't get me wrong, I'm also in favour of considering the peduncle as an
integral part of the inflorescence. But just the definitions above are not
strong enough to support this. 

It is not difficult to modify the definitions as: 

1. Stem: the vegetative part of the axial system of plants bearing leaves and
buds...
2. Inflorescence: the fertile part of the axial system of plants consisting of a
common inflorescence axis and several flowers. The inflorescence axis consists
of a part below the first flower (the peduncle) and a flower bearing part (the
rachis)(*).

But, even this more nuanced definition just reflects an opinion. So, my initial
request still stands: 'to hear some 'arguments' to defend this point of view'. 

(*)[It should be noticed that currently in the PO browser (and in the
APWeb-Glossary) there is some contradiction: rachis is considered as 'synonym'
of inflorescence axis and not as a 'part' of it. At the same time peduncle is
considered as a 'part' of the inflorescence axis while it is evidently not a
'part' of the rachis] 

Guido. 

Dr. Guido Mathieu 
Peperomia Research Group 
Department of Biology 
Ghent University 
K.L. Ledeganckstraat 35, 
B-9000 Gent. Belgium
www.peperomia.net