Category Archives: Gardening

Exobasidium ferrugineae

I found this fleshy, flower-like structure growing on Lyonia ferruginea (rusty staggerbush) at Archbold Biological Station (Venus, Florida). Heaths don’t make flowers like this, so I originally thought it might be an insect gall or phytoplasma infection, but I was wrong. After poking around online I think it’s Exobasidium ferrugineae, a Basidiomycetes fungus. Members of the genus grow in between cells of flower and leaf tissue, then in the Spring send hymenial tissue through stomata and other cracks in the epidermis, eventually turning the surface white with spores. I’d never heard of such fungi before. I’ve led a sheltered life.

Colin Purrington Photography: Fungi &emdash; Exobasidium ferruginea on rusty staggerbush (Lyonia ferruginea)

The above was the largest structure I found (perhaps 3 inches high) but there were dozens of others (see below) at the same location. If you’d like to know more about the species and genus, a good starting point is Kennedy et al. 2012 and references therein. In older literature the fungus was known as Exobasidium vaccinii (Burt 1915), but it seems likely that that species is host specific to Vaccinium vitis-idaea.

Theobroma cacao flower

Here are some close-ups of Theobroma cacao flowers at Longwood Gardens in Kennett Square. The plant is economically important (because chocolate) so people fuss over pollination a lot, but its bizarre floral anatomy is noteworthy regardless of the species value. The catchiest structures are the pointy red staminodes, stamens that became neutered over evolutionary time, which probably have roles in visual attraction of pollinators (ceratopogonid midges) and in preventing self pollination. The real stamens are enclosed in translucent petal pouches, though I chose to photograph this flower because one of the anthers has popped out.

Colin Purrington Photography: Plants &emdash; Theobroma cacao flower

According to one scenario I read, the flies first land on the exterior of the pouch, then crawl inside to lap up nectar from minute glands on the adaxial surface near the anthers. During their foraging they get coated with pollen, and some of the pollen gets deposited on the style (small white structure encircled by the staminodes) when they exit the pouch. Here’s a close-up that shows the translucent pouches:

Theobroma cacao anther sacs

Presumably some of transferred pollen is from previous visits at different trees (because most types are self-incompatible). These flies do such a terrible job pollinating that farmers often just do it themselves with paintbrushes and forceps. There’s even speculation that the domestication of T. cacao some 1500 years ago slowly changed the plant enough that the original pollinator(s) (bees?) were lost, with the midges being the only insects still interested in the meager nectar rewards.

The photograph below shows the cauliflory habit of the flowers, and the “parallel staminodes” variant of the flower.

Colin Purrington Photography: Plants &emdash; Theobroma cacao flower

Shaving your legs to deter ticks

Male American dog tick (Dermacentor variabilis) crawling on human leg.

People shave their legs for a variety of reasons: to look younger (artificial neoteny), to look less like men, to show off tattoos, to show off muscle definition, to improve athletic performance (less drag, plus fools brain into thinking you’re going fast), to facilitate post-accident wound cleaning (cyclists), and because shaved legs induces a pleasurable sensory overload (at least to some). But can shaving also protect you from ticks? I became curious this week after watching a tick crawl up my leg. I was really surprised to discover that no experiments on this topic have been done, but did succeed in finding three relevant snippets on the internet (two from mountain bikers, one from cross country runner):

“One thing that helps is shaving your legs. Not a foolproof way but I would say it reduces them critters by 80%, maybe more. I noticed that when my wife and I were out and she had none, I had around 14 that day.” source

“As an experiment I shaved my legs before riding point to point at lbl with KRS and a few others. It was tick season. After 40+ miles of riding I had 1 tick on my sock. Along the way KRS pulled OVER 15 ticks. We rode the same route at the same pace. I’ve kept the hair off ever since.”  source

“I’d say its mostly impractical. Although, I know many trail runners (including myself sometimes in the summer) do it to prevent ticks from attaching.” source

But, hey, maybe the anecdotes are just that, and hairy legs actually deter ticks in some way.

But it makes sense that shaving would deter ticks. The first is obvious: ticks can grip hair, so if you are hairless (and are wearing shorts, skirt, or kilt), they can’t climb as fast (they are headed for your groin, by the way). The second is that you if you have hairless legs you can most likely better feel them crawling up your legs. I.e., all eight of their legs are touching your skin’s sensory array (or all six of their legs if they are larvae). The third is that when you remove all your leg hair you are removing a lot of sensory distractions caused by wind (experiment on swimmers), and thus you can zero in on things crawling on you. Indeed, all of these mechanisms might touch on why we evolved to be relatively hairless in the first place.

So about the experiments that need to be done …

An easy way to assess would be to count numbers of ticks on a group of people out for a walk, some of whom shave. But at least in the United States, that would break down to men versus women, and males smell worse than women and thus might attract more ticks, regardless of hirsuteness. And men are usually larger, so there’s the surface area thing that goes against us, too. So it would be far better to recruit a group of hairy-legged women and ask them to shave just one leg, then march around a field known to have ticks. Participants would tie white bandanas around their upper thighs to arrest the ticks before they got too intimate, then count tick numbers. But finding enough women who don’t shave might make the protocol hard to follow (again, at least in the United States). So perhaps using a group of guys would be more feasible. An ideal group might be a men’s college swim team right before the season begins. Just ask the coach to donate their legs for science. Would be an easy publication for a day’s work, and the experiment would be crazy photogenic. Plus great team-building exercise. Would get the college on the evening news I’m sure.

A simpler design might be to just have a motivated group of people (perhaps students in a field ecology course?) conduct tick races on shaved, unshaved legs. You just need to start them on the ankles and have participants hold still while the ticks make their ascents. That would be equally photogenic and fun, I think. And to get at the perception part, you could have blindfolded participants that would be asked to identify location of ticks crawling up legs (with controls being placement of non-ticks on ankles, perhaps).

The proposed experiments might seem horrific, but just the for record, I once swam around the edges of a small pond just to see how many leeches would attach to me. I recall that my father challenged me, and that we were going to see who could win. I don’t remember who ended up with more. (Yes, that was a nerd x testosterone interaction effect.)

If somebody does go ahead and conducts this experiment — and if the effect is huge (my guess) — the next step would be to alert the folks at the CDC so they could add a shaving recommendation to their tick page. The reaction to that would be entertaining.

Girl with shaven legs