Well November is here and it's come around quick. Despite the gloom of this week winter is still holding off, and much of the garden seems to be in a kind of stasis.
With this in mind and following on from the Plant Botany course at the start of the month I thought it might be interesting to take a look at some of the oldest 'plant' forms that exist around us starting with two that sit in a grey zone next to plants, algae and lichens.
Algae, specifically green algae shown above, bear some similarities to plants such as containing chlorophyll (green pigmentation) and some were the ancestors of land plants. However their cellular organisation and biochemistry differs enough for them not to be considered true plants.
Lichens, though also often put together with plants are their own grouping. There are many different types, and each one is a symbiotic relationship between an alga or
cyanobacterium and one fungus or multiple fungi. In general they are comprised of a central layer of cyanobacteria or algae cells, which are photosynthetic, and outer layers of fungal cells, which both protect and allow water storage and transport. Lichens are divided into three groups;
Crustose: these are the thin crusts that grow on surfaces of trees, metal, stone, etc
Foliose: these are slightly thicker with almost flattened like plates
Fruticose: these are much more branching resembling mini shrubs with some pustule-like forms.
The fungal part of each lichen grows into a form much like the leaves of a tree or arms of a coral to give the maximum area for photosynthesis and food production.
The earliest members of the 'true' plant kingdom are the mosses, liverworts, and hornworts, thought to have evolved about 450-430 million years ago. In their biology they are a long way from the flowering plants, and in many ways resemble lichens and algae far more closely. They lack the vascular water and sugar transport systems of more recently evolved plant species, and do not have leaves, roots and stems as such.
They alternate between the green form that many of us are familiar with (the gametophyte generation), and the production of little green/brown hairs/protrusions (the sporophyte generation).
The green/gametophyte generation is perennial, photosynthetic, and grows outwards to collect water and minerals. The sporophyte generation is entirely dependant on the food and nutrients from the gametophyte.
As the first plants to really move from an amphibious environment to the land the mosses, liverworts, and hornworts are still reliant on water to carry their spores to other locations. Without roots they absorb the water they need from the surrounding atmosphere hence why they are often found in damp and moist environments.
All of these plants and quasi-plants have changed little in many millions of years. They have found a form that works in their own evolutionary niche. Despite being small they have many beautiful shapes, colours and textures. Take a magnifying glass and have a closer look at those around you.
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