A Tree-Spotter's Guide to Fruits and Seeds: Part 6

Medlar Mespilus germanica isn't a native tree in Britain and it doesn't seem to produce many viable seeds here, but it has been naturalised in a few hedges in southern counties. It's also quite widely planted in botanic gardens, on account of its large, attractive white flowers in spring, vibrant yellow autumn foliage and these curious fruits. Medlars need to be softened by frosts and a period of natural decay after they ripen - a process known as 'bletting' - before they are ready to eat. They have a slightly resinous flavour and are a bit of an acquired taste but I quite like them. There's a tree loaded with the fruits that I pass every day and as soon as the frost has done its work I'll make some medlar jelly - unless someone gets to the tree before me. I've tried to germinate the seeds from the fruits, with a complete lack of success.

The fruits of common lime Tilia x europaea are unmistakeable, being attached to a leaf like bract that slows their fall and allows them to spin to earth when they're released from the tree. It's not as aerodynamically efficient as the winged seeds of sycamores or ash, judging from the concentration of lime seeds that end up very close to the parent tree. Many of the seeds are sterile.

Folklore has it that a heavy holly berry crop is a sign of a hard winter to come. What it really indicates is that back in late May, when the trees were flowering, conditions were good for pollinating insects to carry pollen between the separate male and female trees. Trees with no berries at this time of year are most likely males, which can't produce berries, or females that were too far from a male to be pollinated. Some cultivated hollies carry flowers that are hermaphrodite and always produce berries. There's also a rather attractive yellow-berried form.

Stately elms that once graced the landscape are now history, thanks to the ravages of Dutch elm disease, but shrubby hedgerow elm is still common enough. Its clusters of crimson flowers produce masses of discus-shaped winged seeds - but they are all sterile. Hedgerow elms were all propagated from cuttings, so they were all genetically identical and all equally susceptible to the lethal fungus - only a few mature trees have survived.

For more on tree identification click here

Grasshopper

We came upon this male field grasshopper Chorthippus brunneus sunbathing on the steps down to Hawthorn Hive on the Durham Coast, this afternoon. His courting days are over and he was making the most of the warm mid-day sun, before the frosts arrive and bring an end to his short life. Somewhere there will be packets of eggs, carefully inserted amongst grass roots by his mate who he would have serenaded by sawing the pegs on his legs back and forward across those membranous wings, in the process of stridulation.  Next spring they'll hatch and the nymphs that emerge will grow and moult four times before they reach maturity - and then the next generation of chirruping grasshoppers will begin the whole cycle all over again.
You can listen to a field grasshopper's song here

For more grasshoppers, click here

A Tree-Spotter's Guide to Bark: Part 1

When you think about it, the bark of a tree is pretty remarkable. It's the tree's self-healing protective layer, defending the thin layer of living phloem cells inside, just below the surface, that conduct sugars up and down the stem and also protecting the living layer of cambial cells that produces new growth every year. It's waterproof, but it lets gases pass in and out and it's capable of expanding to keep pace with the growth of the tree, splitting and cracking as the tree ages in a pattern that's characteristic of each tree species. On one January day twenty-seven years ago the bark of this beech Fagus sylvatica was the canvas on which SP and CS carved a declaration of their undying affection; thankfully the wound healing properties of the bark meant that the tree still thrives, even though the union of SP and CS may or may not have endured.

The bark is a tree species' fingerprint. This is Scots pine Pinus sylvestris, with its irregular plates of warm red-brown bark that perfectly complement the deep, glossy green of its needles - especially when winter sunlight strikes the trunk.

The barks of pedunculate oak Quercus robur and of Durmast oak Q. petraea can't really be distinguished, so this could be either (although I happen to know that it was the latter because the acorns had no stalks). I think it may generally be the case that slow-growing trees like oak develop a rugged bark of ridges and fissures that are slowly added to with age, while fast growing species like sycamore and birch tend to develop more rugged splits or shed bark more readily. 

Sycamore Acer pseudoplatanus bark is smooth when the tree is young but soon develops into flattened, irregular plates that are slowly shed as the tree ages, flaking away to reveal a fresh layer below.

For more posts on tree ID click here