What the nose knows: Hemizygia petiolata

It seems that the sense of smell varies greatly from person to person, for example I've heard it said that some people cannot detect the fragrance of freesias (I most definitely can). There are two extraordinarily smelly plants that I grow, among many with scented foliage, among which at least some of my students and myself detect individual differences in what we smell. The first is Agathosma gonaquensis, to me it smells like garlic, to most others it smells like skunk--so strong (the oder volatizes at times into the air) that I brought the plant home, where it does not bother myself nor my wife and stepdaughter. The second one is the plant pictured, Hemizygia petiolata. The description from my source, Silverhill, says it smells like coconut, and indeed some of my students also detect a coconut or suntan lotion like smell. To me it is a most obnoxious smell, though I do detect a certain sweetness to it, it also has strongly annoying quality to it. A quick survey on the net discloses that an essential oil is made from it and marketed, and there is also research suggesting that some of the oil components resemble alarm pheromones in some aphid species, so it may have repellant qualities for some insect pests. I can certify, however, that whiteflies have no such issue with it, they consider it salad.

I continue to grow it because it is interesting, easy to grow, and deer don't touch it in the school garden. White flowers are borne on slender terminal spikes which are themselves topped with small light purple bracts. No doubt the flowers would put on more of a show in places with milder falls and winters, but here the flowers come so late that there is little time to enjoy them before frost does them in. It would make an interesting addition to a herb garden.

H. petiolata is not cold hardy, so I take cuttings or dig up the roots for overwintering under lights in my classroom. One year I had plants in pots which were brought in as they started to flower, and with hand pollination a few seeds could be set indoors.