Plant Detective Case 1: Malva assurgentiflora

It’s been a productive few months for plant detective work, something that not all readers may be aware I spend a lot of time on. This might sound like something that isn’t an important job, but I would argue it’s very important for agroforestry in such a climate as the West Coast, where there just aren’t that many safe choices. That work to find more safe choices hasn’t been done yet, and we can’t just copy other regions, as e.g. what might be a safe choice in Canterbury such as apricots, might not work at all on the West Coast (apricots indeed do very poorly on the West coast). There are also a lot of plants that don’t seem to do particularly well in other areas of New Zealand that do extremely well on the West Coast (e.g. yangmei is growing very fast for us with very healthy dark green growth), and trialing is really the best way to find these things out.

In the interests of finding ‘new’, highly suited plants for our unusual climate, I have to track down plants that may be in New Zealand, but are very rare. Usually these plants are not in active cultivation. Sometimes it’s possible to re-import these plants as seeds, and sometimes it isn’t (in which case tracking it down becomes a lot more important as there isn’t a usable pathway to legally add new species to import into New Zealand). There are enough ‘cases’ worth of investigation here to fill a series of posts, so we’ll give it a go.

First in the spotlight is Island mallow (Malva assurgentiflora). Before I discuss this plant, let’s just look at it:

Stunning, isn’t it? Island mallow (Malva assurgentiflora, formerly Lavatera assurgentiflora) is a beautiful plant in the Malvaceae family. A large percentage of this family is edible as leaf and flower crops (abutilon, hibiscus, hollyhock, linden, okra – to name a few). They’re often very beautiful as well. I’ve been expanding the number of species from this family we’re growing as a result. The concept of growing edible ornamentals is sometimes called ‘edimentals‘ – something the brilliant Stephen Barstow came up with. Abutilons are definitely ‘edimental’, and grow very well for us, but their flowers are the real crop – the leaves are a bit too fibrous. Would be nice to have much more edimentals (these are a great ‘gateway’ to getting more people to grow edible plants), so that’s one area we’re actively researching.

One of the ways in which I look for new plants is to look at particular climates that match well with the New Zealand climate. For example, some parts of Eastern Australia, Western Chile, Western United Kingdom, Western United States & Canada are fairly similar to the current climate of the West Coast of New Zealand. However, this is a rather surface level analysis. To look deeper, we need to consider that plants (in general) haven’t evolved much at all and haven’t moved too far within the last (e.g.) 100,000 years – but within that timeframe they have passed through ice ages (also see this relevant xkcd). As a result, to find suitable plants, we don’t consider just the current climate the plant is located in, but also the previous climates the plant has been through. Some ‘desert’ plants for example are really just forest plants that became stuck and had to adapt over a long period (millions of years) to desert life, and they still contain within them the genes to succeed in a wetter environment (e.g. carob – which grows very well on the West Coast surprisingly). Some plants that are found in tropical environments are also stuck there and do much better in places that are much cooler (bunya, Torreya taxifolia). This is such a crucial and important concept that I will be writing at least another whole article on this subject – stay tuned.

So to get back to the chase, I have been looking for these plants that are adapted to a wetter & cooler climate, but are perhaps trapped in some place unsuitable. One place I looked to find interesting plants is the Channel islands. No, not the Channel Islands in the English Channel, but the Channel Islands off the coast of California (did you know California has islands?). Coastal California is home to some of the most successful exotic species that grow in New Zealand, and what’s more – these plants are now rather poorly adapted to California and are often endangered to some degree. It’s hard to believe, but Pinus radiata is one such species – in California it is endangered – in New Zealand it’s one of the most invasive exotic species that we have. Macrocarpa (Cupressus macrocarpa) is considered vulnerable in California yet grows incredibly well in New Zealand (cypress canker notwithstanding). Coast redwood – similar story. Notice a pattern? Endangered plants in coastal California, are often highly adapted to New Zealand conditions, because they’re actually wanting to grow in a cooler & wetter climate and did so for hundreds of thousands of years (at least), but have become ‘trapped’ in a rapidly desertifying California.

So on the Channel islands, off the coast of California we have a look for interesting species. Malva assurgentiflora pops out as one interesting plant on the list – and it’s ‘Critically Imperiled’ in habitat. Pretty much every Malva species is edible, so that’s a given. It definitely looks very beautiful in photos. The next step is to see if this species can be imported or otherwise exists in New Zealand. Well it turns out that not only does it exist, but it has escaped cultivation and is growing in coastal Christchurch! This is exactly what we predicted from the patterns we identified from semi-endangered coastal California plants – that it would be well suited to New Zealand conditions. There don’t seem to be any nurseries selling plants, so it’s off to search for Island mallow it is (I could’ve imported seeds in this specific case, but that’s not as fun of a story, is it).

The next stage in the story is to try and track down these Island mallows somewhere in Christchurch. With Caleb B, we were able to locate the patch quite rapidly:

Having located it, it was time for the taste test. As I mentioned, since it’s a Malva, it’s practically guaranteed to be edible, so I had no concerns. The flower was the first thing I tasted. Hmm, it wasn’t sweet like an abutilon and was also a lot chewier, and definitely not that good (not worth coming all the way for!). Hmmm… well better taste the leaf then… wow! It’s delicious!

The leaf was far tastier than the flower, being slightly crunchy (possibly an adaptation to store water in a drier environment?) and with a distinct lack of fibres (unlike abutilons). They tasted very nice and were possibly even a little sweet. They are probably among the best tasting of all Malvaceae leaves I have tasted, and may even take the top spot.

Rumours of this plant escaping cultivation are highly exaggerated however. Both patches we found were very near to older cultivated gardens, and there was practically no seedling regeneration at all (I found only 3 seedlings in total). The few plants we found were extremely healthy though, large sprawling shrubs with bright green leaves and no sign of damage (nothing from salt, cold or insects). These plants had clearly been living for a few years – Island mallow is a longer term perennial unlike some of the other Malva species commonly found in New Zealand which tend to die after a few years. What was self-seeding profusely was Malva arborea, which grew within a 1 metre distance and had dozens to hundreds of seedlings, but by contrast all of these M. arborea seedlings had yellow leaves with fungal infections.

Well, we gathered some seeds of Island mallow. Possibly I have already germinated a few dozen already, but I’m not 100% certain yet as the soil I put the seeds into while collecting would’ve contained many other weed seeds.

It still remains to be seen how Island mallow would grow on the West Coast, so the story is definitely not over yet. But that will be a later update. Plenty more plant detective stories to come 🙂