Tag Archives: botany

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

Boating to Bartram’s Garden

One of the gems of Philadelphia is the former estate of John Bartram, a world-renowned botanist and buddy of Ben Franklin (who flew his kite there, I gather). Back in the day, his garden along the Schuykill River was filled with rare and interesting plants collected from different regions of the colonies, had a heated greenhouse, and was a destination for anyone of import who happened to be in the area.  The garden and buildings today survive on a small patch of the former property, an island amid urban squalor and decaying industrial sites.  You can drive there, but I took a boat from downtown Philadelphia (visit www.schuylkillbanks.org for details).  In case you are too far away to do the same, some photographs are below (mouseover reveals description; click to see larger).  The most notable part of the house tour was the thriving population of camel crickets on the ceiling.  The tour guide was annoyed that everyone was so interested in them. If you’re in the area and want to go, get details at bartramsgardens.org. The anniversary of his death is this Sunday (September 22nd).

Colin Purrington Photography: Philadelphia &emdash; Boat to Bartram's Gardens on the Schuykill River

Colin Purrington Photography: Philadelphia &emdash; Bartram House

Colin Purrington Photography: Philadelphia &emdash; Strange staircase at Bartram House

Colin Purrington Photography: Philadelphia &emdash; Camel crickets on ceiling of Bartram House

Colin Purrington Photography: Philadelphia &emdash; Specimens on desk in Bartram House