Sunday, November 29, 2009

Angophora costata

The Sydney Red Gum, Angophora costata, is a particularly beautiful tree, especially in spring when its normally smooth bark flakes away to expose the new season's pinky-grey bark beneath.

Angophora costata1

Angophora costata is found across a range of eastern coastal regions in Australia, and they are common in the sandstone soil of the Hawkesbury area. They are not of the genus Eucalyptus, but are closely related. One way to distinguish them is that Angophora leaves grow opposite each other on the stem, while in Eucalyptus species they alternate.

Angophora costata2

We have a few mature specimens in our garden, and they provide shade and habitat for a multitude of creatures. Their heavy limbs also have a tendency to shatter, alas. Just over two years ago, a large tree fell over on our house.

I recently bought a pair of earrings made from A. costata leaves. The leaves were treated with acid, removing all leaf tissue but the skeleton, and then dipped in gold. It's not easy to see from this photo, but against the light you can see the filigree pattern. Ideal for a planty person's lobes!


Wednesday, November 11, 2009

Fauna less loved: bloodsuckers.

I often wax lyrical in this blog about the flora and fauna in our garden, but some species are less welcome than others. Here are a couple of invertebrates that can make gardening a little hazardous.

This is a paralysis tick, Ixodes holocyclus. It's only tiny when it hasn't been feeding: this specimen is only 1.5mm in body length.When they're engorged with blood, they increase in size by many times.

Ixodes holocyclus

Ixodes holocyclus is indigenous to the east coast of Australia, and its food source is primarily the blood of marsupials such as wallabies, bandicoots and possums. Domestic cats and dogs are particularly vulnerable to them in bushland areas, and without treatment can die. Human fatalities have become far less common since the development of an anti-toxin.A couple of months ago, a paralysis tick made its way into my bra, and injected me with its toxin. By next day, the inflammation on my breast (lovely soft flesh--a tick's delight!) was the size of a saucer, raised, hot and very painful. It took a course of antibiotics, antihistamines, steroid cream and many sleepless nights before it subsided.

Ticks are in the class Arachnida, like spiders and scorpions, and thus have eight legs.

Another bloodsucker frequenting our garden is the leech. The species below is (most likely) the Australian Land Leech, Gnatbobdellida libbata, which has evolved to live out of water, and becomes active after rain.


While waiting for prey, the leech anchors itself by its posterior sucker and raises its body up. It senses potential victims by vibrations and chemical sensing, and attaches to the skin by its mouth. Then it injects anticoagulants and histamines to stop the blood from clotting and allow it to flow freely into the leech. Amazingly, it's easy to miss that a leech has attached to you. It's only after it's full and drops off to digest your precious bodily fluids, that you notice the itch---and the blood freely pouring out of the wound. If you're prone to allergies, like me, a nasty hot, itchy welt can develop.

Much as I loathe their effect, I do have a grudging admiration for leeches. They mark a significant evolutionary development from less derived species, because their body segmentation improves their mobility--something very evident when you watch one weaving through the air after it's sensed your presence. Leeches are hermaphrodites, and cross-fertilise during sex. In the phylum Annelida, they are related to common garden worms, but most of their near relatives are marine.

Next time, friendlier species, I promise!