Survival Strategies of Plants on Shoreham Beach. Talk given by Joy Daintree, followed by having a detailed look at specimens. For the first half of

Transcription

1 Survival Strategies of Plants on Shoreham Beach. Talk given by Joy Daintree, followed by having a detailed look at specimens. For the first half of this session, Joy gave an illustrated talk about the various plants which are found on Shoreham Beach and how they are adapted to the harsh and changing conditions there. Joy was speaking from her deep knowledge gained as an active member of the Friends of Shoreham Beach, and we all found the talk most interesting. Here are the illustrations from her talk, interspersed with photos of the leaves and section through the leaves of some of the plants mentioned. We discovered all sorts of things!

2 The common orache is an annual which speads all over the loose gravel just above the high tide mark as the Summer progresses, to form a carpet. It was the wrong time of th year for us to find leaves and look at them.

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7 We managed to find some sea beet plants with tap roots in the garden, and here is a rather mushed section through the tap root of one of them. You can see how the middle of it is just made up of a white mush and no visible cells, and the white mush is probably starch which can be used to provide energy for the growing plant in the Spring before the sunlight gets very strong.

8 We had a look at the leaves of biting stonecrop. Seen under the micrsocope, they were very rounded and shiny, with a waxy surface. When we cut a thin slice through the leaf, you could see how bulbous the shape was

9 When we magnified it we could even see the layer of wax on the outside, and under it the green cells ful of chlorophyl. We could also see the large bulbous waterstorage cells inside the leaf.

10 We didn t have any leaves of thrift, but we did have leaves of sea mayweed and fennel and buckshorn plantain. Here are two views of the top of the sea mayweed leaves, you can see how narrow they are compared with the leaves of a common daisy. The leaves are also waxy, to prevent them drying out, and quite thick being a bit glabrous. Here is a close up of the top surface, showing little blobs of what appears to be wax. You can also see the cells. The underneath of the leaf is very folded, to stop the wind from getting at the leaf to dry it out. You can see that the underside also has the little stars of wax on it, and how deep the groove is down the centre of the leaves.

11 Here is a section through a sea mayweed leaf. You can see how narrow and curled it is, and how it is a bit glabrous to store water in its inner cells, and how it is coated with wax. This rather a thick ssection and at a funny angle so that you can see part of the outer surface of the leaf at the bottom of the photo. At the top right you can see the long shaped chlorophyl containing outer cells with wax out sie them. Fennel turned out to be very similar, but even more pronounced. It was too fine for me to take sections without the right equipment (still to be unearthed from my hold!) top surface and here are two photos of the underside of the leaves; you can see how folded they are, the pale parts being the underside of the leaves and the dark parts are the folded over waxy edges of the topside of the leaf.

12 It was when we got onto the hairy leaves thay we had lots of surprises, with much enthusiatic look what I ve found! or they ve got double tips! etc for the hairs turned out to be very varied! Apparently the proper name for the hairs or spines or bristles is trichomes. We didn t have any mouse eared hawkweed, but we did have ribbed plantain, silver leaved ragwort, tree mallow and yellow horned poppy leaves. Because all of these were very different, I;m going to put them all in here. Firstly the ribbed plantain. It s leaves are very different to the buckshorn plantain which theyre are photos of above. They are folded into ridges or ribs, and are hairy. Here is a photo of a section through a leaf which broken in half, but you can see the ridges. And a section through one of the ribs. Both surfaces are covered with very fine hairs. There seem to be more in the dipes than on the ridges to cut down the air movement. You can see the hairs on this outer edge of the cut section I the middle photo.

13 The silver leaved ragwort turned out to be quite different. Both the top and the bottom of the leaf seemed to be covered by a sort of spaghetti of hairs, rather like the fleece they put over plants in the winter. Here are views of the top and bottom of the leaves: -At the edges of the leaves and in the sections you can see what a thick layer of straggly trichomes make up the what silvery affect on the leaves. The leaves of the tree mallow are very soft; as some one said they feel like velvet and would make a nice pillow! When we looked at them we found that they were covered with long hairs (or trichomes) all lined up in the same direction from stalk to rim of the leaf, and very fine. Unfortunately I lost the original photos we took and the leaf I used afterwards was wet, so didn t whow the neat arrangement of the spines. You can get some idea how many there were from these photos, and also how long and fine they were:- The hairs show up very vividly in these two photos of sections through the leaves : - Aren t they beautiful? In this photo you can see how they seem to grow in little tufts. They seem to be made in one piece like the ones in the ribbed plantain, but are they hollow?

14 The leaves of the yellow horned poppy gave us a great surprise because they looked (to the naked eye) so like the silver leaved ragwort, but under the microscope were totally different to both the ribbed plantain and the tree mallow. As we investigated further, looking at them at a higher magnification and at the edge of cross sections through the leaf, we came to the conclusion that the trichomes/hairs seemed to be hollow what do you think? I haven t managed to find anything online about the structure of these trichomes maybe we are the first to have looked at them under the microscope?

15 Some of the leaves we looked at above had a waxy surface which you could see in our photos, for example the biting stonecrop and the rock samphire. The really waxy sea kale wasn t available for us, since it s not in leaf yet. We did have a look at the see beet leaves though. They were very shiny to look at, though not white with wax like the sea kale looks as if it must be. Because the leaves of the sea beet were so shiny they didn t photograph well, and the wax on the leaf was easiest to see in this oblique section through the leaf. wax

16 The bristly and knobbly leaves also turned out to be fun to look at! First we looked at the bristly oxtongue leaves:- At first sight we thought the bristles (trichomes) were rather like the hairs we had seen on some of the other leaves, and then we realised that they were simple spikes but had interesting ends Sometimes we got a section showing the base of one of the trichomes see next page

17 and we thought that the trichomes/bristles/hairs might not be hollow, but filled with something. Also they didn t seem to be in sections like the hairs on the yellow horned poppy. What do you think? We were surprised to find a tiny greenfly nymph on one of the bristly oxtongue leaves! I have uploaded all the photos we took and you can see them here is you want to look into all this a bit further :-

18 It wasn the right season to be able to illustrate these, but if you go for a walk on the beach you will be able to look for yourself.

19 This was such an interesting session because of all Joy told us, and how we were able to see what she was talking about for ourselves, as well as making new discoveries! Thank you Joy!