Is pace of life more conservative than body size, among families of plants?

(writing in progress)

I have known for decades that body size in plants is remarkably plastic, within taxa.

There are innumerable genera of plants in which some spp. have small bodies, and others have large bodies. This can easily be seen in information on the maximum heights.

To mention just one example: Euphorbia varies from tiny herbaceous species to tall trees (https://en.wikipedia.org/wiki/Euphorbia). Members of this genus vary from a few centimetres high (e.g. https://en.wikipedia.org/wiki/Euphorbia_prostrata) to 20 metres (https://en.wikipedia.org/wiki/Euphorbia_candelabrum).

This plasticity in plant height, within families, is noticeable among genera and also within species.

However, a related idea has been more peripheral in my mind, possibly because it cannot be seen as such. I refer to pace of life, viz. the rate at which organisms use energy for metabolism, growth, and reproduction.

(Pace of life is most biologically meaningful when expressed relative to body mass, according to allometry (https://en.wikipedia.org/wiki/Allometry).)

I have the impression that pace of life follows the opposite trend from body size in plants. That is to say, that pace of life may be among the least plastic, and most conservative, aspects of plant biology, tending to be consistent with families, regardless of the plasticity in plant size.

There are various clues to pace of life in plants.

One is specialisation for either poor soils (which suggests slow pace of life) or rich soils (which suggests fast pace of life).

Oligotrophic plants are specialised for soils, such as deep siliceous sands, that are poor in all nutrients. A prime example is Proteaceae (https://en.wikipedia.org/wiki/Proteaceae).

Eutrophic plants are specialised for soils, such as alluvial loans, that are rich in all nutrients. A prime example is Brassicaceae (including Capparaceae, https://en.wikipedia.org/wiki/Brassicaceae and https://en.wikipedia.org/wiki/Capparaceae).

Proteas vary in plant height from a few cm to 25 m (https://en.wikipedia.org/wiki/Banksia_integrifolia). However, all are adapted to poor soils, or those that, if dystrophic, tend to be poor in catabolic nutrients such as zinc (https://en.wikipedia.org/wiki/Catabolism).

Brassicas vary in plant height from a few cm to 12 m (https://en.wikipedia.org/wiki/Boscia_salicifolia). However, all are adapted to rich soils, or those that, if dystrophic, tend to be rich in catabolic nutrients such as zinc.

(writing in progress)

Posted on November 01, 2022 10:59 PM by milewski milewski

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