Richard Bell's nature sketchbook since 1998
From molehills to mountains: the moors on the tops of the Pennines are still covered with snow. We returned to Charlotte’s Ice Cream parlour at Whitely this morning, a regular coffee stop in the days when we had my mum in tow. It was often the one day of the week that she got out and, despite her deteriorating eyesight, she always appreciated the panorama . . . and of course the coffee and the scone.
I must take after her. Oh dear!
Over the weekend I noticed that the mole has extended its excavations into the flower border below the bird feeders. For the last few weeks that single molehill, right in the middle of the lawn, had been the only sign of its activity.
If I can infer the layout of its tunnels from the heaps of earth above ground, the main tunnel runs west northwest to east northeast. This is along the contour of the slope. Would a down-slope tunnel be at more risk of flooding?
Red food colouring added to the water and taken up by a plant stem reveals the arrangement of xylem tubes in a cross section. Xylem tubes transport water up the stem from roots to leaves and flowers. These two stems had been left in the solution for two days.
Each yogurt drink container started out with 100 millilitres of water. As you’d expect, the daffodil took up more than the leafless stick of celery, eight millilitres as opposed to the five. There was no detectable evaporation from the container filled with water only.
The experiment reveals that the xylem tubes in the daffodil, a monocot, are loosely clustered around the centre of the stem whereas in the celery, a eudicot, the xylem tubes appear more organised, arranged around the central pith along the edge of the stem.
Monocots are flowering plants that are so called because the emerging seedlings have one seed leaf (cotyledon). They typically have parallel veins in their leaves. Monocots include onions, bluebells, grasses and maize.
Dicots have two seed leaves and typically have a network of veins in their leaves.
Eudicot means ‘perfect dicot’. The eudicot clade (group) includes the majority of dicots but excludes basal angiosperms such as hornworts, water lilies, magnolias, avocado* and bay laurel, the herb that gives us bay leaves.
*We’ve just returned from the farm shop and noticed that on our bill the assistant had misidentified the avocado (Basal Angiosperm;clade Magnoliidae; order Laurales) as a lime (Angiosperm; clade Eudicotyledonae; order, Sapindales). I can see how you could mix these up! We still think that the fruit on the right is an avocado but we won’t feel totally sure until we cut into it. The texture feels different to the lemon; it doesn’t have the same give in it, so it’s not ripe yet.
It’s been suggested that avocados evolved their fruits – which botanically are berries – containing one large seed, to be eaten by large mammals that have since become extinct, such as Megatherium, one of the giant ground sloths.
I’ve been reading various books on botany and enjoying these two online resources:
From Roots to Riches: Our changing relationship with plants over the last 250 years – from tools to exploit, to objects of beauty, to being an essential global resource we have to conserve. Presented by Prof Kathy Willis. BBC Radio 4, Kew Gardens.
E O Wilson’s Life on Earth available as a free download from iBooks. Part 5 introduces Plant Physiology, which includes the experiment to demonstrate the properties of xylem.