An introduction to trees
Trees are sometimes taken for granted, they play such a big part on our surroundings, holding together the soils and increasing the biodiversity of the given habitat. Britain has around 60 native species, the reason for this low amount is because of the changes in environment so suddenly. For example with the ice age, it doesn’t give the trees enough time to recolonise. Leaf identification is an obvious way to find out the tree species as you can look at the leaf shape, colour and markings, texture and margins. Also you can look at how it is arranged on the stem/twig, the flowers, buds and fruits that it bears.
An introduction to angiosperms (the flowering plant)
The angiosperms start off with either one leaf (monocots) or two embryonic leaves (dicots), there are at least 260,000 species. There are so many different species as where ever you go, whatever habitat you find, they will always be there. There is a high variety between the species but they each have similar deriving features.
A main feature in flowering plants is the ovary position, there are three types of positioning on the plant. They are, superior (the ovary sits on top of the receptacle), inferior (sits in the receptacle) and a semi-inferior (which is where it sits in between). The amount of petals is important too. Monocots have an even amount of petals and dicots always have an odd number. The leaves are also a useful way to identify – monocots have long leaves, whereas dicots have rounder leaves. These leaves, like with trees can be pinnate, palmate, a simple structure, lobed or toothed, or lobely toothed also the positioning on the stem is just as important.
An introduction to gymnosperms (seed bearing plants)
Gymnosperms have now been put into four divisions, each with “naked seeds”. The groups are cycads where there are 140 species and they all have a pinately compound leaf structure. The ginkgo group has only one species left in it, which originates from China. The Coniferophyta division is the largest out of the 4, as it includes all trees like cedar, spruces, firs and yew. The Gnetophyta is the division which links angiosperms with the gymnosperms, as the species in the group have flowers. All of the other groups are just seed bearing. The leaves between all the gymnosperm divisions vary highly, as the conifers drop their leaves whereas there are others that are large, leathery and have a simple structure.
An introduction to lower plants
The difference between gymno/angiosperms and bryophytes and vascular plants is that the latter produce spores not seeds. The Bryophytes (non-vascular plants) are the sorts that first colonise bare land include species like the Foliose liverwort, which is a marchantiophyta. Within the lower plant subject there are many different divisions. These marchantiophytae are the simplest of plants, as they have no roots, no stomata and have a single cell rhizoid.
An introduction to Mosses
There is a main aesthetical difference between mosses and liverworts, the leaves of liverworts are deeply lobed, and the mosses have a separate stem and leaf structure all together, it is more complex than the liverwort. There are 10,000 species of Bryophyta in 700 genera all of which thrive in damp, shady areas. These species produce spore capsules and, unlike the liverworts, they have multi cellular rhizoids.
There are three major genus which are; sphagnus, which are quite common and are found in acidic, waterlogged areas, they also have round spores. Mountain mosses which are found in rocky areas, these are the type that have a lantern type capsule, then lastly there’s the arthrodontous (bryopsida) which take up about 90% of all mosses, these have a toothed capsule. There are two forms of bryopsida; arcocarpous which grow upright and have their capsule at the tip of the stem, then also the other is pleupcarpous, these are different as they have creeping branches and at the side of these branches they have their capsules. Then Hornworts, are different again as the Thallus is a crinkly plate, but also the capsule, when ripe, it splits into two stems. They are most like the liverwort regarding the simple celled structure.
An introduction to Ferns
The Pteridophyta division includes seedless vascular plants Lycopodiophyta (Club mosses), Sphenophyta (Horse tails) which have spores and they produce a cone at the tip. Another defining feature is the small leaves that grow at the nodes, there is only one genus left in this division, which is the Equisetum.
Then the ferns, they still have no true leaves but have short veins of a primitive nature. Their fronds uncurl as they mature, releasing a leaf with many leaflets on which have their spores grouped together on the underside and as a group it is called a Sori. It is through these spores that they reproduce sexually, but they can also reproduce asexually via the vegetative rhizomes.
There are different ways that you can identify a fern, they include looking at the actual size, though age could be dependant. Then their habitat and how they grow for example if they grow in groups or isolated, then the leaf structure, as you would with trees, whether the Ramenta is present or absent, if present the colour of it can help.