Monday, 1 February 2021

Going Urban - part 2

 In the last post I touched on plants that find niches in urban environments by growing in cracks and various other nooks and crannies in our human world. The second group of plants that can be studied and recorded in urban environments are initially planted but eventually become a part of the landscape. Many people who get involved in plant surveys don't record such things, which is a shame, because they are certainly a part of the world around us and they will be having an effect on any number of things, especially populations of insects that may find them appealing. It is also worth noting that the Botanical Society of Britain and Ireland (BSBI) certainly encourage street trees to be recorded.

My recent visit into Cromer on the North Norfolk to get the car its annual MOT certificate gave me the opportunity to do some plant recording in town and to muse on a few things regarding urban botany, this time looking more at the exotics that come into our everyday lives, rather than the colonisation of our space by native species...

Linking in from the last blog post, as this is a plant on a wall, is this Felicia petiolata. One of the benefits of recording non-native plants in urban environments is that it gives us a chance to monitor the progress of these species. Many will be pretty innocuous and cause no problems for the environment around us, but every invasive alien started somewhere and we can acquire a lot more accurate data on the rate of spread of a species (or otherwise) if we record it right from the start. Felicia petiolata (which appears not yet to to have earned itself an English name!) is a relatively recent addition to the suite of plants available to gardeners through the horticultural trade. I found this plant where it had self-seeded into a lovely old Norfolk wall in Stiffkey nearly five years ago and it will be interesting to return at some point and see if it is still thriving. This species is from South Africa and is sold as a half-hardy plant for hanging baskets, but it does seem to be starting to get through our winters OK and it is a perennial, so could become the next Mexican Fleabane!
One obvious barrier to becoming established is hardiness - the ability of a plant to survive cold weather. For plants from warmer climes, this can be a major issue, although many plants are able to withstand periods of cold, even ice and frost, if they are dry and it is the UK's wet winters that can be a problem for them. This species is Giant Viper's-bugloss Echium pininana which is native to La Palma, one of the Canary Islands. For many years now it is done well in the milder parts of south-west Britain, but winters are getting milder and plants are not only surviving the winter to attain flowering size (which takes two to three years) but its seeds are germinating and young plants are starting to appear outside of gardens in a number of places, even here in East Anglia. This plant is in my garden, but it shows how frosty weather can make it have second thoughts! (The wilting of leaves is actually a good strategy to protect the stem of the plant from the worst of the weather)

Palm trees are perhaps one of the most iconic indicators of a tropical or sub-tropical climate and are popular for use in holiday hotel gardens in warmer regions of the world. The so-called 'English Riviera' in South Devon once prided itself as the only part of the UK where palms managed to survive reasonably well, thanks to a coastal climate and the effects of the Gulf Stream. But times are changing and is clear to see in the plants that local authorities choose to spend money on. At first, palms were a brave choice and only for the mildest of coastal towns, where no doubt a few extra degrees of warmth from the urban environment helped them survive. Such plants were also often lifted and placed under cover for the winter, or heavily lagged in hessian to help them survive the worst of the winter weather. Such cultivation techniques essentially rendered these plants unrecordable to botanists since they are clearly not surviving without help, but this is not so much the case any more. Chusan Palm Trachycarpus fortunei from China has coped with UK winters for many years now and recently I even found some self-sown seedlings from one. But other species are starting to appear and this picture shows Dwarf Fan Palm Chamaerops humilis which is a Mediterranean species of warm, stony places. I think that, as well as recording the presence of these street plants where they are clearly continuing to grow unaided through cultivation, it will be useful to establish what year they were planted as an aid to monitoring how survival might change over time - another useful addition to phenology projects.

As things get more exotic in response to our changing climate, local authorities get more ambitious with what they are prepared to put out onto our streets. With my botanist's hat on, this offers up a great opportunity to delve into unknown areas in search of identifications! From a distance, I assumed this tree would be one of the date palms in the genus Phoenix, since they are reasonably tolerable of cold weather and the species from the Canary Islands is quit popular as an ornamental. After taking a few close-ups of some of the finer details, I delved into the scary world of palm identification and realised that it's a species of Butia from southern South America. It's a difficult group so I'm going to have to wait for the fruits to develop a little more but I think it's going to be either Butia capitata or Butia yatay - time will tell, and time will tell if it thrives but it's already survived a couple of winters at least, I believe.

Some plants are smaller than trees but they are still perennial plants with permanent above-ground structures so are worthy of recording where they are clearly not being cultivated and tended. The New Zealand Flaxes were introduced to the UK in great quantity in the 1970s and since then have become familiar sights around the country. Again, they are a little susceptible to winter weather damage, so recording will be an interesting way to see how they are coping here. As with the palms, the presence of these plants has meant time spent delving into identification sources for plants from other countries and it is amazing what is possible now that we have the internet. Although I checked on the progress of this plant in Cromer on my recent visit, this photo was taken last summer as the flowers are the feature that best allows us to tell the two species that we have in the UK apart from each other.

A closer look at the Cromer plant reveals the flowers to be mostly yellowish in colour and with petals that are quite strongly recurved at the mouth of the flower. These features - as well as the relatively short height of the plant overall - make it Lesser New Zealand Flax Phormium colensoi, which is often grown on a range of forms with variegated or coloured leaves.

For comparison, these are the flowers of New Zealand Flax Phormium tenax, a much taller plant with stouter leaves. Note that the flowers are deep red in colour and the petal tips are not as strongly recurved at the mouth.

Bamboos have progressively become quite a growth industry (excuse the pun!) and some of these large grasses certainly have a proven track record for potentially being aggressive growers and becoming invasive. Thus, recording of plants found outside of parks and gardens is a useful practice that could provide some good data for the future. It doesn't seem all that long ago when pretty much every bamboo you found was going to be Arrow Bamboo Pseudosasa japonica, which was handy because bamboos can be notoriously difficult to identify! Increasingly, however, bamboos have been marketed as the 'must have' accessory for the garden and other species are now to be expected and need to be taken into consideration. On the outskirts of Cromer this week, I found an interesting assemblage of plants on some untended, rough ground that had clearly been planted by someone in the past but which showed no recent signs of cultivation. Among the hotch potch of plants was a couple of bamboos, so it was time for a full suite of photos and some research back home. This one eventually gave itself up as Umbrella Bamboo Fargesia murielae, the first time I have found this one while out and about with my recording sheets.

A closer look at the amazingly polished, rich olive-green stems of Umbrella Bamboo. The leaves are distinctive, too, with their very long, drawn out tips.

Growing not far from the Umbrella Bamboo was another species of this distinctive group of plants. Luckily, this one had stems like polished ebony and it was soon clear that this is Black Bamboo Phyllostachys nigra and another species I have not come across outside of gardens before. Things are clearly changing in our world and getting out and recording that change continues to be an integral and important part in understanding what is going on and how to accommodate it.

As part of the suite of photos that I take of bamboos to assist identification, I always photograph a leaf while holding it up to the light. The number and arrangement of veins in the leaf can be useful in the identification process, but this shot of Black Bamboo also offers a nice, arty finish to this post!

No comments:

Post a comment