Walnuts and their allies
 

What advantage do walnuts and their relatives gain from having the
kernels of their nuts such an unusual shape? From my non-walnut point
of view it seems that having so many sticking-out bits increases the
risk of mechanical damage and drying-out.

Mike.

Walnuts and their allies
 

Mike Lyle schreef
What advantage do walnuts and their relatives gain from having the
kernels of their nuts such an unusual shape? From my non-walnut point
of view it seems that having so many sticking-out bits increases the
risk of mechanical damage and drying-out.

Mike.

+ + +
Once upon a time this would have been an easy question.
It was to resemble to a brain, so as to show walnuts were "brain food".
PvR

Walnuts and their allies
 

In article ,
[Mike Lyle] wrote...

What advantage do walnuts and their relatives gain from having the
kernels of their nuts such an unusual shape? From my non-walnut point
of view it seems that having so many sticking-out bits increases the
risk of mechanical damage and drying-out.

Good question. But of course the lobes and sticking-out bits
are kept fairly safe inside the shell, even after germination.
[The seedlings are of the hypogeal type in the familiar members
of the walnut family].

One thought that occurs to me is that lobed and dissected food-storage
tissues in seeds may be partly protected from insect damage. There are
teh familiar plates of not-so-edible, fairly hard tissue between the
lobes. An insect attacking the seed might tend to confine its activities
to a single lobe, or at least it would have a harder time making a meal
of the whole seed.

Although the lobed seed structures in the walnut family [Juglandaceae]
are the cotyledons of the seedling, the situation is reminiscent of
something called "ruminate endosperm" that is found in many other
families of flowering plants. In these plants the food-storage tissue
of the seeds is endosperm, which is lobed and dissected by plates and
strands of hard inedible sclerenchyma tissue.

An insect trying to eat such endosperm might have difficulty tunneling
through it, compared to one living in a similar seed without ruminate
[meaning ="chewed"?] endosperm.

A ref:

Occurrence and taxonomic significance of ruminate
endosperm.Bayer Clemens Appel Oliver
1996 The Botanical Review;
Ruminate endosperm is characterized by its uneven and enlarged
surface. A list of 58 angiosperm families in which this trait is
known to occur is presented. The simultaneous presence of
different rumination types in angiosperms and even within single
families leads to the conclusion that ruminate endosperm has
originated several times in parallel. Therefore, the mere occurrence
of rumination does not provide evidence for phylogenetic
hypotheses. Nevertheless, rumination features can provide
valuable characters for taxonomic purposes, [snip]

cheers

Walnuts and their allies
 

Walnuts and their allies
 

In article ,
(mel turner) wrote:
In article ,
[Mike Lyle] wrote...

What advantage do walnuts and their relatives gain from having the
kernels of their nuts such an unusual shape? From my non-walnut point
of view it seems that having so many sticking-out bits increases the
risk of mechanical damage and drying-out.

Since we're speculating :) ...

What about the issue of extended surface area versus weight?

Two possibilities come to mind:

1. Quicker and more uniform wetting of the tissue during germination,

and, somewhat from the other point of view,

2. More effective aeration (and/or drying :) of the tissue during
metabolism (and/or after partial imbibition).

Good question. But of course the lobes and sticking-out bits
are kept fairly safe inside the shell, even after germination.
[The seedlings are of the hypogeal type in the familiar members
of the walnut family].

One thought that occurs to me is that lobed and dissected food-storage
tissues in seeds may be partly protected from insect damage. There are
teh familiar plates of not-so-edible, fairly hard tissue between the
lobes. An insect attacking the seed might tend to confine its activities
to a single lobe, or at least it would have a harder time making a meal
of the whole seed.

Although the lobed seed structures in the walnut family [Juglandaceae]
are the cotyledons of the seedling, the situation is reminiscent of
something called "ruminate endosperm" that is found in many other
families of flowering plants. In these plants the food-storage tissue
of the seeds is endosperm, which is lobed and dissected by plates and
strands of hard inedible sclerenchyma tissue.

An insect trying to eat such endosperm might have difficulty tunneling
through it, compared to one living in a similar seed without ruminate
[meaning ="chewed"?] endosperm.

A ref:

Occurrence and taxonomic significance of ruminate
endosperm.Bayer Clemens Appel Oliver
1996 The Botanical Review;
Ruminate endosperm is characterized by its uneven and enlarged
surface. A list of 58 angiosperm families in which this trait is
known to occur is presented. The simultaneous presence of
different rumination types in angiosperms and even within single
families leads to the conclusion that ruminate endosperm has
originated several times in parallel. Therefore, the mere occurrence
of rumination does not provide evidence for phylogenetic
hypotheses. Nevertheless, rumination features can provide
valuable characters for taxonomic purposes, [snip]

cheers


Cheers, Phred.

--
LID

Walnuts and their allies
 

mel turner schreef
Good question. But of course the lobes and sticking-out bits
are kept fairly safe inside the shell, even after germination.
[The seedlings are of the hypogeal type in the familiar members
of the walnut family].

One thought that occurs to me is that lobed and dissected food-storage
tissues in seeds may be partly protected from insect damage. There are
teh familiar plates of not-so-edible, fairly hard tissue between the
lobes. An insect attacking the seed might tend to confine its activities
to a single lobe, or at least it would have a harder time making a meal
of the whole seed.

Although the lobed seed structures in the walnut family [Juglandaceae]
are the cotyledons of the seedling, the situation is reminiscent of
something called "ruminate endosperm" that is found in many other
families of flowering plants. In these plants the food-storage tissue
of the seeds is endosperm, which is lobed and dissected by plates and
strands of hard inedible sclerenchyma tissue.

An insect trying to eat such endosperm might have difficulty tunneling
through it, compared to one living in a similar seed without ruminate
[meaning ="chewed"?] endosperm.

+ + +
Who knows? A consideration is that walnuts for their dispersal rely upon
their edibility, like acorns. Also the "hard" bits between the lobes are
surely less so when walnuts are fresh.
PvR

PS walnuts are not nuts.
PS II according to Harris and Harris indeed "ruminate" = "wrinkled, as if
chewed"

Walnuts and their allies
 

Xref: 127.0.0.1 sci.bio.botany:21184

PS walnuts are not nuts.

Why not, & if not, what are they?

Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)

Walnuts and their allies
 

PS walnuts are not nuts.

Iris Cohen schreef
Why not, & if not, what are they?

DAGS?
PvR

Walnuts and their allies
 

In article , Iris Cohen
writes
PS walnuts are not nuts.

Why not, & if not, what are they?

Judd et al say that they're drupes.
--
Stewart Robert Hinsley

Walnuts and their allies
 

PS walnuts are not nuts.

, Iris Cohen writes
Why not, & if not, what are they?

Stewart Robert Hinsley schreef
Judd & al. say that they're drupes.

+ + +
So does everybody else. A nut is a hard dry fruit, eg. an acorn.
The walnut tree has a thick well-fleshed fruit, of which the pericarp is
commonly called a husk.

Walnuts are drupes, as are coconuts. As to peanuts ...
PvR