letting nature back in

Here is a serendipitous juxtaposition: a longhorned beetle on our patch of New Zealand spinach. I use the word serendipitous because it was unforeseen and opportune, and because serendipitous has a great positive ring to it.

I have not seen this beetle in our garden before, so it is an unusual visitor. It is a real beauty – the iridescent green is eye-catching, as are the alternating colours of auburn and black on its legs and long antennae.

The longhorn beetle family (Cerambycidae) is large, comprising over 20 000 species, and from what I can gather, its classification (taxonomy) is complex and subject to ongoing revision. Most longhorn beetles are fulling winged and can fly, with some species being nocturnal, and others diurnal. Like crickets and some other insects, they can stridulate; they can emit a rasping or squeaking noise by rubbing their legs over ridges on the body.

The larvae of longhorned beetles are wood borers. Most longhorned beetles lay their eggs on freshly cut or damaged timber, but some use healthy, living trees as hosts, which can be harmed by the boring larvae. Some species can cause damage to fruit trees, others to timber plantations, and some bore into cut and untreated timber, including timber used in buildings, rafters for example.

As far as I can tell, this beetle photographed in our garden is an Evgenius plumatus. I can find very little information about this particular species, other than that there is a trade in dead and mounted specimens for collectors. As there is information more readily available on beetles that are categorised as pests, because of the economic impact of the damage the larvae cause to host plants or timber, I am guessing that this particular species is not considered to be a problem, hence the absence of information.

In the adult (beetle) form, most longhorn beetles require some sort of food, although there a few species where the adults do not feed at all. For those that do feed, different species eat different things. Some eat bark or stems, others stems, twigs or buds, and some eat sap or fruit. Which of these the Evgenius plumatus eats, I have not been able to find out. I did not see this individual feeding on the New Zealand spinach plants, even though it spent most of the day on them. So it seems its visit to these plants was serendipitous only for me, because I could photograph it, but was purely incidental for the beetle.

Apparently then, New Zealand spinach does not provide food for the Evgenius plumatus longhorn beetle, but it is a food source for us. It is easy to grow (at least in milder climates or in summer) and easy to harvest. I just snip off the shoots with a pair of scissors. It can be used like Swiss chard (it has a milder taste) and English spinach, and it is cooked in a similar way.

Like Swiss chard and English spinach, New Zealand spinach has relatively high levels of oxalic acid, with the level at its highest later in the season when the plant is flowering. Most green leafy plants contain oxalic acid to varying degrees. It is recommended that when preparing plants with relatively high oxalic acid levels for cooking that the leaves should be blanched for a few minutes in just-boiled water and the water discarded before using the leaves, but there is also the view that unless one is consuming huge quantities or using older leaves, it is not essential.

Other foods relatively high in oxalic acid include bran flakes, rhubarb, beets, potato chips, French fries, and nuts and nut butters. It is recommended that these foods are eaten in moderation, especially by people who might be prone to forming kidney stones. According to the Cleveland Clinic, anyone worried about kidney stones would do well to limit the intake of foods high in oxalic acid, and in addition consume food and beverages high in calcium, keep well hydrated by drinking enough water, avoid eating large amounts of protein, and have a low-sodium (salt) diet. Vitamin C intake should not exceed the recommended daily allowance. Perhaps this is good advice to inform anyone’s eating habits. For more see here.

New Zealand spinach (Tetragonia tetragonioides) is known by several names, including Botany Bay spinach, Cook’s cabbage, Tetragon and Warrigal greens. It is native to Australia, some of New Zealand’s offshore islands, and other countries around the Pacific Ocean including Japan, Chile and Argentina.  In the wild, it is mostly a shoreline plant but also occurs naturally in inland salt marshes. It has naturalised in other habitats and in other parts of the world, including here in South Africa. In some regions and countries it is utilised as a commercial food crop or is at least used in domestic vegetable gardens, in others it is regarded as an invasive alien.

Our garden plants were propagated from cuttings we collected from plants growing wild in rocky crevices above the beach at Ballito just north of Durban. When we visited Sydney in Australia we saw them growing wild at the top of the cliffs of the South Head. The plants look more straggly under these windswept coastal conditions, but in the garden, as can be seen in the photo above, the growth is very lush.

The plant has small yellow flowers and produces masses of seed as can be seen in this picture. It self-seeds readily, so we leave it to self-propagate, which it has done successfully for many years, with no help from us. You just need to recognise the seedlings and only weed out the ones you don’t need to keep

Some sources I have read suggest that it was not used as a food plant by Aboriginal people in Australia, although it may have been in some areas under certain conditions.  Despite the fact that the plant was rarely utilised as food by Maori people on the islands visited by Europeans sailing in the region in the mid-18^th century, the plant was harvested, cooked and pickled and used to prevent scurvy (it is a good source of Vitamin C) in sailors, notably on the ship the Endeavour under the leadership of Captain Cook. It was also used as a replacement for spinach by European settlers in Australia and New Zealand. Joseph Banks, the botanist travelling with Captain Cook, took seeds back to Kew Gardens in the United Kingdom, and it did gain some popularity as a cultivated vegetable.

New Zealand spinach, freshly picked from our garden being prepared for cooking. At this stage it can be blanched, prior to being added to the other ingredients. (The lemon looks rather pale as it has already lost its zest!)

I thought I would share with you one of our favourite and easy-to-prepare meals (adapted from a recipe in River Cottage Veg Everyday). Fry some onion and add the finely grated zest of a lemon, some chopped garlic, red chili and ground cumin. Once fried, add a tin of tomatoes (chop them up) or chopped fresh tomato. Allow it to simmer until saucy. Then add a cup or two of cooked (or tinned) chickpeas and about two cups (raw) of chopped New Zealand spinach. Serve with rice or a bread of your choice. As certain celebrity chefs like to say: Yum!

Quick and easy chickpea tomato spicy stew with New Zealand spinach

Sources:

Cleveland Clinic: Kidney Stones: Oxalate-Controlled Diet http://my.clevelandclinic.org/health/articles/kidney-stones-oxalate-controlled-diet;  Fearnley-Whittingstall, H. 2011. River Cottage Veg Everyday. London: Bloomsbury;  T.E.R:R.A.I.N – Taranaki Educational Resource: Research, Analysis and Information Network  http://www.terrain.net.nz/friends-of-te-henui-group/plants-native-botanical-names-r-to-z/tetragonia-tetragonioides-n-z-spinach.html;   Roskruge, N. 2011. The commercialisation of kōkihi  or New Zealand spinach (Tetragonia tetragonioides) in New Zealand. Agronomy New Zealand  41: pp. 149-156   https://www.doc-developpement-durable.org/file/Culture-plantes-alimentaires/FICHES_PLANTES/tetragone-cornue/The%20commercialisation%20of%20kokihi%20or%20New%20Zealand%20spinach%20in%20New%20Zealand.pdf;     Scholtz, C.H. and Holm, E. 1985. Insects of Southern Africa. Durban: Butterworths.

Posted by Carol