What is an Ecotype?

Gardeners are familiar with different plant phenotypes. For example, I grow White Icicle carrot which has a white root. It is a distinct and different cultivar of carrot. It was selected in a garden for horticulture because of its distinctive phenotype.

Gardeners know tomatoes come in many sizes, forms and colours. Each is a distinctive expression of the phenotype even though they are the same plant species with the same genetic makeup.

An ecotype is a naturally occurring variant in which the phenotypic differences are too few or too subtle to warrant the plant being classified as a subspecies. The guiding hand of nature – natural selection – avoids any need for the guiding hand of the gardener.

Different ecotypes can occur in the same geographic region where distinct habitats such as grassland, forest, swamp and dune-land provide different ecological niches. Or different ecotypes may occur in widely separated places in different habitats. In the instance I’m about to discuss these different places and habitats are evergreen rainforest of Queensland and sandstone country of Arnhem Land in the Northern Territory.

I’m familiar with and have grown Mackinlaya macrosciadea sourced from humid, near coastal rainforest in Queensland.

I’ve grown this indigenous relative of ivy for many years because it’s a pleasingly curious shrub-like understory plant. Not a true tree nor a true shrub, but something in between. In Queensland’s rainforest it grows to 5m tall and foliage and stems are a lush green. They have distinctively bright blue-grey fruit enclosing the seed and in far northern Queensland the fruit are eaten by the cassowary.

image of blue-grey fruit of Mackinlaya macrosciadea
Mackinlaya macrosciadea fruit (Queensland provenance, Wynnum).

Mackinlaya is a genus in the Araliaceae family with five known species found in Indonesia, Northern Australia, New Guinea, the Solomon Islands and the Philippines. Mackinlaya macrosciadea is indigenous to Australia.

But when I encountered this plant growing under a rock shelter in Arnhem Land, the form and appearance was distinctly different – starting with the almost luminous blue-green foliage. Perhaps this colouration is a consequence of shade, perhaps a consequence of different pigmentation (rather like that white carrot).

Mackinlaya macrosciadea (Arnhem Land provenance).

In the Northern Territory, this plant is called the blue umbrella.

In Queensland, it’s very green. Whatever lead to the various differences in form of this plant in the Northern Territory – as shown in the video – they are an expression of natural selection, so this is quite possibly an ecotype.

view up through the canopy  of Mackinlaya macrosciadea
Mackinlaya macrosciadea (Queensland provenance, Eaton’s Hill).

Jerry Coleby-Williams
Director, Seed Savers Network

31st July 2022

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