Education

Winter’s bark Drimys winteri is certainly full of toxins, warburganal and polygodial. Both of these have a very peppery taste, most likely to deter browsing from animals or insects. This was not used in any animal habitat as too slow to establish and only available as small plants usually. Such an interesting plant from a very old family with fossils dating back about 125 million years and an original distribution around the southern hemisphere. Drimys is Greek for acrid, an apt description for the bark. The specific epithet relates to Captain Winter, who sailed around the world with Francis Drake 1577-1580. Rounding Cape Horn and with a sick crew, he landed to seek supplies. The bark of Drimys (which is green inside), boiled in a stew no doubt, was found to be an excellent remedy for scurvy, an awful disease caused by insufficient Vitamin C. This was centuries before Vitamin C was actually described. Now, you do not need to strip the bark to get a flavour of the peppery taste. A very small amount of leaf chewed gently will work very well, but it takes a minute or two to work. It may be best if there are some sweets to pass around to anyone complaining when sampled so as to remove the sometimes uncomfortable hot taste. A great way to make a visit memorable.

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Drimys winteri in full flower is quite a spectacle. The large evergreen leaves still look good in winter.

Spurge Euphorbia, a common garden plant, with several species in various places around the zoo from a very varied genus of about 2,000 species, ranging from annual weeds to large trees. The milky-coloured latex-like sap has lots of potential toxins causing digestive problems or skin irritation. The seed dispersal can be explosive. Each seed pod splitting and violently throwing the seeds out. Euphorbiaceae is unique in having all three forms of photosynthesis in different species, though they are a bit complicated to explain as part of an educational tour. CAM Crassulacean Acid Metabolism photosynthesis evolved in dry climates. The stomata (breathing pores) close in sunshine but open at night to take in carbon dioxide, which is stored for use the next day. First discovered in the genus Crassula, hence the name. CAM is found in Bromeliads for the same reason and in some water plants as carbon dioxide is more readily available at night when dissolved in water. There are different forms of photosynthesis. C3 is the most commonly found in over 90% of all plants but is dependent on sufficient soil moisture, moderate temperature, and sunlight – no extremes. C4 developed later and is a much more efficient method, using only a third of the water needed for C3 photosynthesis, tolerant of higher temperatures and stronger sunlight. Most grasses are C4, thriving in drier habitats than C3 plants could. Think savanna grasses and scattered trees

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Euphorbia rigida and Crassula sarcocaulis, both plants that use CAM photosynthesis. Here, growing along the edge of the savanna trail.