It's been a while since I read the novels in the Speaker Trilogy, so most of what is written down is from recollection...
[The question came up thinking about the relation between all the life forms of pequeninos.]
First of all, is there such a thing?
Are all wives/sisters destined to become a mothertree, ie. do they all enter the third life?
And can there be more than one mothertree in a forest/tribe, or only one? The forest next to Milagre had 'only' one mothertree (during the events of the Speaker Trilogy), but maybe one forest can have several mothertrees?
If they would exist, what would they be called?
A Sistertree (the term sisters is mentioned in a conversation between the Hive Queen and Human)?
Or a Wivetree (which just does not sound right)?
Is a mothertree almost on the same level as a fathertree (they belong to the same philotic network, but are mute until they get the help of Jane)?
Or are they actually more similar to brothertrees (ie. more on the same level), who are also kind of 'mute' (both are able to still communicate with 'second-life'-pequeninos)?
And do brothertrees still hava an aiua or not? Are brothertrees part of the philotic network of the fathertrees and the mothertees (who both DO have an aiua to be part of the network)?
Do brothertrees really communicate, or do they merely respond? However, they do sacrificy themself)
To recapiltulate, this is my depiction of all life forms of the pequeninos:
Let's start with the result of the little mothers (inside a mothertree) who are imregnated by a fathertree and which give birth to a limited number of infants, male and/or female.
The first life life forms:
male infants (inside mothertree): they all become a brother.
female infants (inside mothertree): some become a wife, but most are destined to be little mothers (closing the circle on the female side).
little mothers: they are imregnated by a fathertree and give birth - inside the mothertree - to a limited number of infants, male and/or female (and die in the process).
Second life life forms (as from they leave the inside of the mothertree untill they are full grown):
brothers: they get the honour to become a fathertree, or they are planted without the necessary rituals and they become a mere brothertree.
wives: they (can) become a mothertree (as for now)
Third life life forms [*] :
brothertree: not sure if they belong here or not?, are they still alive, as they can sacrifice themselves?, ie. is their aiua still present or not?
(sistertree): under speculation =^D
fathertree: they 'mate' with little mothers (closing the circle on the male side), and they do have an offspring, sons and daughters, up unto an entire forest/tribe, ... (cfr. the father-forest of Skysplitter or something like that)
mothertree: they serve as the birthing place, they don't have an offspring