As I headed for some note taking I was stopped in my tracks by a new breed of students......
Wednesday, 23 May 2012
Conference call
As I headed for some note taking I was stopped in my tracks by a new breed of students......
Wednesday, 16 May 2012
Hidden beauties #15
Card 15 - Male shield fern
Ferns are one of my favourite plants.
Ferns are one of my favourite plants.
Fern flora on a garden wall
Fascination of ferns
Tuesday, 15 May 2012
Monday, 14 May 2012
Hidden beauties #13
Card 13 - Catching by hairs
I seem to be meeting my self set blogging challenge to post every day (apart from weekends - a "rule" I set up en route). The cigarette cards have certainly provided food for thought, not least a realisation that there are projects I have had in my mind for a long time and have done nothing about. Seeing this picture of grass reminds me that I want to set up a series of pictures of flowers we don't notice - grass flowers, tree flowers, things like plantain. Then there is Spirogyra and other pond life that are so easy to obtain and look at.
Tomorrow I am expecting the arrival of a new microscope, so no excuses ..... At the moment things are quite fraught with student support note taking, but that is only to last another week or so and then I can begin!
I seem to be meeting my self set blogging challenge to post every day (apart from weekends - a "rule" I set up en route). The cigarette cards have certainly provided food for thought, not least a realisation that there are projects I have had in my mind for a long time and have done nothing about. Seeing this picture of grass reminds me that I want to set up a series of pictures of flowers we don't notice - grass flowers, tree flowers, things like plantain. Then there is Spirogyra and other pond life that are so easy to obtain and look at.
Tomorrow I am expecting the arrival of a new microscope, so no excuses ..... At the moment things are quite fraught with student support note taking, but that is only to last another week or so and then I can begin!
Friday, 11 May 2012
Thursday, 10 May 2012
Hidden beauties #11
Card 11 - A leaf slice
As can be seen from the following images, leaf structure can be quite varied, but the overall "plan" is quite similar. The upper epidermis protects the leaf and then underneath that is usually the palisade layer; this is the layer where most of the photosynthesis takes place, its cells are usually tall and cylindrical and well supplied with chloroplasts.. Beneath this layer are the more loosely packed and irregularly shaped cells of the spongy mesophyll layer; beneath that is the lower epidermis. Most of the stomata are usually found in this layer. Carbon dioxide enters the leaf through the stomata and diffuses through to the palisade cells to be combined with water (brought in from the root via the xylem tissue) to form carbohydrates using light energy from the sun.
More information can be found in this article I wrote for Microscopy UK
As can be seen from the following images, leaf structure can be quite varied, but the overall "plan" is quite similar. The upper epidermis protects the leaf and then underneath that is usually the palisade layer; this is the layer where most of the photosynthesis takes place, its cells are usually tall and cylindrical and well supplied with chloroplasts.. Beneath this layer are the more loosely packed and irregularly shaped cells of the spongy mesophyll layer; beneath that is the lower epidermis. Most of the stomata are usually found in this layer. Carbon dioxide enters the leaf through the stomata and diffuses through to the palisade cells to be combined with water (brought in from the root via the xylem tissue) to form carbohydrates using light energy from the sun.
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| Pampas grass - transverse section through leaf |
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| Pinguilica (Butterwort) TS through leaf showing mucilage secreting hair which helps trap insects |
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| Marram grass TS through leaf. Marram grass needs to conserve water so the leaf is curled, stomata are situated in pits,. |
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| TS through the leaf of a xerophyte (a plant that lives in dry conditions) - its epidermis is thick to reduce water loss by transpiration, its stomata are in pits which are surrounded by hairs to increase humidity around them and so reduce water loss by transpiration. |
More information can be found in this article I wrote for Microscopy UK
Wednesday, 9 May 2012
Hidden beauties #10
Card 10 - An airing apparatus
Hmmm, rather a broad sweeping statement to say that pondweed has no external beauty!
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| Potamogeton transverse section through stem |
The image above is another one I took from a prepared microscope slide, again, the colouration is due to stains used to make tissues more obvious. The air spaces which keep the plant buoyant are clearly visible. Buoyancy is necessary to keep the leaves near the surface so that photosynthesis can be maximised. The dark structure in the middle is the vascular tissue, this central arrangement gives the stem more flexibility in moving water. In non woody land plants the vascular tissue is often arranged near the edge of the stem to form a strengthening cylinder; in contrast, root vascular tissue is arranged centrally, thus providing more strength against pulling forces.
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