terminology when evergreens keep or replace leaves

[rtdrury]

It's clear that deciduous and evergreen do and do not go dormant.  But what terminology describes species that replace their leaves annually versus others that seem to keep their leaves forever?  I have mangos with leaves still there at the base of a 4" dia. trunk tthat were there when the plant was 1 foot tall!  Grumichama also seems to keep all leaves forever.  But avocados clearly replace all their leaves annually.  What do we call these two types of plants?  Keepers and replacers?

[TonyinCC]

I have heard the term tardily deciduous used to describe live oaks replacing leaves in Spring.

[Daintree]

Trees that drop their leaves in the fall in response to weather are deciduous.

Trees that hold dead leaves through the winter dormant period are marcescent.

Tropical trees do not go dormant, and also have no "growth rings" to tell their age.
They have several mechanisms for leave replacement.  They may hold their leaves for long periods, often years. They may shed a few leaves at a time all year long,  or shed their leaves yearly but do not go dormant.  They are called semi-deciduous.

Carolyn

[drymifolia]

Trees that drop their leaves in the fall in response to weather are deciduous.

Trees that hold dead leaves through the winter dormant period are marcescent.

Tropical trees do not go dormant, and also have no "growth rings" to tell their age.
They have several mechanisms for leave replacement.  They may hold their leaves for long periods, often years. They may shed a few leaves at a time all year long,  or shed their leaves yearly but do not go dormant.  They are called semi-deciduous.

Carolyn

This is a great summary!

I'm not sure how avocados fit into those categories, though. They do go dormant for the winter (as in no new buds develop), at least when they are grown places with a winter, and they do usually shed the previous year's leaves over a short period near the start of the growing season (right around when the first flush starts hardening, usually, sometimes a little later).

I guess it's just a type of semi-deciduousness?

[Mango Stein]

Wow, getting technical. Most people don't know the difference between foliage and foilage.

Welwitschia has leaves that can last a few thousand years. It is on the coat-of-arms of Namibia. Very unique species. A family with just one genus and one species.

To answer your question, long-lived and indefinite leaves are called persistent. There is even such a thing as persistent fruit; some chokeberries, dogwoods and hawthorns.

Leaves that are replaced are called caducous or fugacious, though I think these terms can be used for both evergreen and deciduous species.

[Fygee]

May not be the most technical term, but I've called them cyclers, since they cycle out their leaves within a specific time period.

[Daintree]

Persistent! That's the word I was trying to think of!
I always think of caducous leaves like baby teeth, they are pushed out by the next leaf coming in.
Ain't botany grand???

Carolyn

[rtdrury]

Seems caducous & persistent are likely terms most may recognize for "leaf replacers" & "leaf keepers".  I just monitor trees and want to know if this leaf drop is routine, or instead from weather stress, hidden root damage, root rot, moles maybe, etc.

[Daintree]

Yeah, I ask my trees all the time "are you dying, or are you just shedding?"
Sometimes they answer me, and sometimes they don't...

[drymifolia]

Yeah, I ask my trees all the time "are you dying, or are you just shedding?"
Sometimes they answer me, and sometimes they don't...

Now that I'm growing dozens of avocado cultivars and hundreds of seedlings, I've finally given up on this question for avocados. It's almost always leaves getting ready to shed, but each cultivar does so in such unique ways I'm always wondering if it's some virus or nutrient deficiency and then a few weeks later the tree drops a batch of leaves.

Here's a great example now:

That is "Not Mexicola," from cuttings purchased on Etsy from someone selling it as Mexicola, but who admitted it was collected from a "feral" tree in a public park that they just assumed was Mexicola based on fruit appearance. It's definitely not Mexicola or Mexicola Grande, I have all three grafted side-by-side and their flushes are noticably different colors. This is the oldest leaf on the graft, so I'm assuming "shedding," but I've never had an avocado that looked quite like this before shedding.

Here's another, this is Marta's "Long South Gate" introduction, which turns bright yellow:


And Duke, which usually gets splotchy with yellow and green:


Some others turn orange or bronze, often with chlorosis along leaf veins. Some also turn brown at the tip before dropping.