Aspen leaves bigger on new growth?

I observe a small clump of healthy Aspen trees approx 20 feet tall in planted naturescape parking area at the coast - and the tops have been cut back a few months ago (it looks not too bad actually, surprisingly)

And what I see now is the new growth over the summer (approx 6 feet tall twigs on top of existing former growth) has much larger leaves than the typical silver dollar size quaking aspen fluttery Leaves

I also notice some volunteer young aspen nearby - they also have the really large leaf diameter compared to typical aspen leaf diameter

Why does young new leaf growth have much larger diameter ?

 

It's consistent with the fact the entire new shoot in each case is bigger than the older, twiggy growth from which it sprang - not just the leaves. While growth farther back on the branch does have more total volume that is dispersed among many more pieces.

 

It's rather common, that water sprouts/suckers have more vigurous growth than normal sprouts. If these trees were pruned/cropped in the middle of the vegetation period, then sleeping buds, that developed to those water sprouts, had much better conditions for development than spring grown sprouts, as those trees were well provided with water, nutrients, warmth and sunlight at cutting time.

 

Yep, they can be substantially larger - up to 20-25 cm long, rarely even 30 cm. They also frequently have a more typical 'poplar-shaped' leaf with an acute apex, not rounded.

 

The ones asked about here are not water sprouts.

 

And what sprouts they are?
AFAIK, sprouts, that often appear after pruning or top pruning, are water sprouts.
According to what I see from the photo above, they are water sprouts.

 

Some of the principles of bonsai: The sizes of leaves are reduced by cutting off all the leaves at once, typically in June when there is enough growing season left to mature a new canopy and buds for next year. All terminal buds must be removed. The new canopy will have smaller leaves all of the same size, ~generally, because all the resources have to be divided among all the buds that are mature enough to grow.

If you just remove all the leaves, but leave all the terminal buds in-place, then fewer tertiary buds will be activated on older wood and the terminal buds will grow like wildfire and you get waterspouts. You get the same thing if you chop a large percentage of branches off, as in Pollarding. The principle is to prevent the tree from growing in a ~normal~ matter of putting the majority of resources in the terminal buds in a emergency response. Instead, forcing the tree to activate dormant buds that would normally never be used on older wood, and subdivide the total amount of resources between a larger number of buds, making more leaves in the canopy with approximately the same total surface area as possible with fewer, larger, leaves. Also, and even more important in bonsai, the following season will have even more buds/leaves/ramification to continue having smaller-than-type leaves, for awhile. Eventually, all growth returns to type when interference stops.

 

QUESTION - it seems within this thread we may have a couple of different definitions of water sprout - so if we agree that these are the absolutely vertical fast whips that grow up from main branches on an old coastal Apple tree ...

Is that whip-like growth caused by
1. Wrong pruning technique
2. Wrong pruning time (too late in spring?)

Or?

It used to be quite common to see this water sprout growth esp in neighbourhoods where people did grow their food in the backyard of the city lot.

 

The very large leaves I mentioned were on the lead stems of vigorous young planted trees, not sprouts.

 

All of the above, and especially damage to a tree like a big branch breaking off. A tree has some specific amount of stored resources in the roots. If something happens to the canopy that greatly reduces the amount of buds available to inflate with those resources, the tree's emergency response is to go into very high growth mode. Any part of the tree that has very good light and air will receive as much of the (now) surplus resources as can be processed to whatever the limits of transpiration are. I hope that a botanist will enlighten us if the vascular system of water spouts are markedly different.