Walk Report – Sept 2018

18 August 2018

For an undemanding ramble with plenty of interesting features, the Denis Heesom Trail has plenty to offer.

So it was that eleven members and guests set off from Jock’s Bay – well, actually from the Harold Porter National Botanical Gardens, down Waterfall and Lipkin Roads to Jock’s Bay – on a sparkling morning, the destination being Stony Point.

Wind pruned vegetation on the Denis Heesom Trail

Cape Seashore Vegetation has to be extraordinarily tough to survive in an environment that is hostile to any but the most cunning of plants.

Survival strategy number one is dwarfism, where shrubs that are familiarly sprawling or erect in less windswept, sun-baked, salt-sprayed habitats hunker down in low growing, tight shrublets against the challenges posed by the sea shore. Polygala myrtifolia is a good example, as are the wind pruned Searsia species at the start of the trail.

Carpobrotus acinaciformis 

Survival strategy number two is succulence. Members of the Aizoaceae family, Tetragonia decumbens, kinkelbos, the famous Carpobrotus edulis, suurvy/sour fig, its more localised relative, Carpobrotus acinaciformis and the remarkable Ruschia macowanii are typical examples of Cape Sea Shore succulents. But even daisies, of the family Asteraceae, develop fleshy, succulent like leaves in this environment, not least one of the objectives of our walk, the late winter/early spring flowering Dimorphotheca fruticosa, rankbietou.

Dimorphotheca fruticosa, Rankbietou on the Denis Heesom Trail

Survival strategy number three involves spending much of the year underground as a bulb, tuber or corm. At this time of year, as we saw all over the place, Cape Sea Shore members of the geophytic family Amaryllidaceae spread their broad leaves on the ground, out of the wind, busily manufacturing the carbohydrates that will power their brief spell of spectacular flowers, Brunsvigia and Haemanthus, towards the end of summer. Iridaceae, of course, do the same geophytic thing. The first flowerings of the rich red Gladiolus cunonius, Lepelblom, caught our eye – quite unlike any other Gladiolus we could name.

One of the Amaryllidaceae getting ready for late summer flowering

We were struck by the veritable greengrocer’s store that is Cape Sea Shore Vegetation. Sea parsley, Dasispermum suffruticosum, of the family Apiaceae (the carrot/celery family); Sea/dune spinach, Tetragonia decumbens, of the family Aizoaceae and sea pumpkin, Arctotheca populifolia, on the dunes. Don’t go looking for pumpkins you can eat though, it’s actually a daisy in the Asteraceae family. You can also find sea lettuce. Okay, so this one isn’t a land plant but seaweed, green algae among the Chlorophyta of the genus Ulva – but you can eat it. It was in the rock pools close to the path, so it counted. Also countable is another seaweed, black sheets of Porphyra capensis, red algae among the Rhodophyta this time, clinging to the rocks. It is closely related to Nori – well known to sushi lovers.

Sea lettuce, Ulva species 

While on the subject of algae, on reaching the beach after adventurously crossing some swiftly flowing streams, we had to stop to marvel at the structure of kelp, Ecklonia maxima, one of the brown algae known as Phaeophyta. Not exactly a gastronomic delight, but well known for its fertilising properties. It’s the growth hormone that is extracted from it that gives gardens such a lift. Kelp has to be one of the most extraordinary forms of algae around – with its root-like holdfast to cling to rocks, gas filled stem, stalk or stipe , which can extend to 12 metres, and bulb at the top to provide flotation support for its fan of strap shaped fronds extending from a flat base and spreading spores far and wide from the edges.

African Penguins, Spheniscus demersus, at Stony Point 

A slow ramble full of interest brought us to the penguins and cormorants at the sea bird breeding colony and Stony Point. Home time.