Dear Readers, petunias are popping up in the hanging baskets and pots of East Finchley. I must confess that I have never been a big fan of the plants, but the great thing about the Wednesday Weed is that it’s made me question everything that I’ve ever known. After all, what is a petunia, and how has it become so popular? What is it related to? Do any insects like it?
Well, petunias come originally from South America – there are about 20 separate species. The plants are members of the Solanaceae or nightshade family, which includes tobacco, tomato and potato, and their name ‘petunia’ comes from the word ‘petun’, meaning ‘tobacco’, in the local Tupi-Guarani language. The Maya and the Inca believe that the plant has the ability to ward off underworld monsters, and there is a belief that petunias bring happiness to a house. They are certainly the most generous of plants, pouring forth their blooms for months at a time. No wonder they are many people’s first choice for a hanging basket.
The ‘domesticated’ petunia is a hybrid between two species, Petunia axillaris (the white moon petunia) and Petunia integerifolia (violet petunia). The white moon petunia has a sweet smell which has been inherited by some forms of the cultivated petunia, while the violet petunia is said to be used as a hallucinogen in Ecuador, giving a sensation of flying.
The cultivated petunia is known as Petunia x atkinsonii. Incidentally, this is an example of a nothospecies – a new word to me, so I had to investigate. A nothospecies is a hybrid between two plants in the same genus, as here. If a plant is a hybrid between two plants of different genuses, it’s known as a nothogenus. Who knew? Certainly not me, who has enough trouble finding two matching socks at the moment.
Anyhoo, back to the petunia. It seems to tolerate drying out better than some other plants, which makes it ideal for the exposed environment of a hanging basket. It isn’t overfond of conditions that are too damp or shady – it is said to need at least five hours of full sunshine every day. It pairs beautifully with pelargoniums (which need similar conditions) and there is definitely a petunia for every colour scheme. There are the ones which are divided into segments:
and my favourite, the ones that look like starry skies….
One definite disadvantage of the petunia from my point of view is that, pretty as it is, it doesn’t seem to attract many insects. All the species bar one are pollinated by insects, and rumour has it that petunias are sometimes visited by hummingbird hawk moths, as evidenced by several photos.Being a plant of hanging baskets, the seeds of petunia are often scattered far and wide, and the seedlings can sometimes be seen popping up in the cracks in the pavement during the following spring. The paving stones by the side of pubs are a particularly good spot – some pubs pride themselves on their floral displays, and there are several in London that really exceed expectations. Perhaps the finest is the Churchill Arms in Kensington, which spends £25,000 a year on its floral display, and very fine it is too.
Allegedly, petunia flowers are edible, though no one seems to get very excited about them. I was a little disappointed to see that the ‘Petunia Bowl’ salad that I found online was an homage to The Hitchhiker’s Guide to the Galaxy (in which two thermonuclear missiles turn into a whale and a bowl of petunias) and actually contains no petunias, though as there is some thought that the petals might be poisonous it’s probably just as well.
Now, here’s a fascinating thing. A couple of caterpillar larvae do eat the flowers of petunias, and both are serious pests of agricultural crops. One, the corn earworm (Helicoverpa zea) is the second most serious insect pest in the USA, munching its way through corn, tomatoes, cotton and a dozen other plants. Not only does it decimate plants but, most unusually for a moth, the caterpillar will also eat other insects.
The other species that feeds on petunia is the cabbage looper caterpillar (Trichoplusia ni) which, as its name suggests, normally prefers brassicas, red cabbage in particular. As this is a vegetable that I find it hard to get excited about, I am prepared to give this little chap rather more garden-room. Plus, it does that ‘inch worm’ walk that I found so appealing when I was a child.
Now, in a study by the scientists at United States Department of Agriculture in Peoria, Illinois, it has been found that when the caterpillars of both species were fed on bi-coloured petunias like the one below, they much preferred the white sections to the coloured ones. When given no choice but to eat the blue bits, they put on much less weight, and a much higher proportion of the larvae died. The hypothesis is that this is due to the natural anthocyanins in the blue petals, which act as a natural insecticide. Such pigments are energetically expensive for a plant to produce, but of course these plants have been bred rather than emerged through natural selection. The question is whether these pigments could have a wider application, and how much effect they would have if they could be bred into food crops. Fascinatiing stuff.
And here’s a poem. I’ve had to read it once or twice to get under its skin, but it’s worth it. I regret that I hadn’t come across Bob Hicok before – he was born in 1960 in Michigan, and had worked for years in the automotive industry before he discovered his gift for poetry. He is most famous in the US for his poem series about the shootings at Virginia Tech. Someone commented that “Hicok’s meditations… do not allow us to turn away from the act of violence, neither from the person who committed the act, nor from the ironies of survival.” See what you think.
The semantics of flowers on Memorial Day
Photo One by By ElenaSchifirnet – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=15124646
Photo Two by By Magnus Manske – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7398799
Photo Three by By EliasTheHorse – I took it on a flower’s shop., CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=74372553
Photo Four by David Short from Windsor, UK [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)]
Photo Five from https://secretldn.com/churchill-arms-flower-pub/
Photo Six by By cyanocorax – https://www.flickr.com/photos/cyanocorax/2901626664/in/set-72157607594253502/, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=7096670
Photo Seven by By Alton N. Sparks, Jr., University of Georgia, United States – This image is Image Number 1327034 at Forestry Images, a source for forest health, natural resources and silviculture images operated by The Bugwood Network at the University of Georgia and the USDA Forest Service., CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=7038081