Purge and repel (Plant Portrait VII*)

If you are after a good laxative or goose repellent, look no further than your closest Rhamnus, Senna/Cassia, aloe or rhubarb (root). You can also select from among certain fungi, lichens and insects.

But take care! This column should definitely not be taken as reliable medical advice and many of these sources are also rather toxic in the wrong quantities. It's also April Fools' Day so who knows what you can believe. And a warning: this post includes chemical and botanical names, as well scatological references.

The active ingredient in life-enhancing (if constipation and geese are your problem) tonics prepared from these critters is called anthraquinone, or when sourced from Rhamnus purshiana (one of the buckthorns), also cascra sagrada.

Leopold Bloom, in Joyce's Ulysses, amuses himself with the efficacy of 'one tabloid of cascara sagrada' as he succeeds in his morning bowel movement on 13 June 1904. (Bloom is reading Mr Philip Beaufoy's column in the magazine Tit-Bits, which he subsequently uses to wipe himself clean.)

Cascara sagrada means sacred bark, a name given to this product by the Spanish arriving in America. It is the bark that is used as a laxative, and that bark contains anthraquinone. The fruit and honey are edible but also have a slight laxative quality.

The light yellow crystals of anthroquinone are also used in the manufacture of 'vat dyes', water-insoluble dyes renowned for their brightness and persistence. You'll find the same chemical in some pesticides and in the production of paper from pulp. Of botanical interest, athroquinone is used to treat seeds of other plants, to ward off various grain-eating birds. It also doubles more generally as a goose repellent.

Anthraquinone can be made soluble by adding reducing chemicals, such as sodium hydrodsulfite. You do this to get it absorbed by the cloth or seed coat before it becomes insoluble again and thereby stays put.

Apart from being insoluble in water, our yellow chemical of choice doesn't interfere with the germination of the seed, and deters but doesn't kill the birds. Birds vomit after eating seed coated in anthraquinone, but they survive to tell the tale. Interestingly, though, some sneaky birds will eat just a few seed - not enough to get sick - and then come back later for a few more.

Rhamnus purshiana is native to western North America and I can't find much record of it growing in Australia. It certainly doesn't appear on our Royal Botanic Gardens plant census. A Portland nursery quotes a description of this species as 'an alder crossed with a birch with a cherry thrown in'. Which is a bit what it looks like in this picture taken by Paul Schlichter, copied from Flora and Fauna Northwest (USA) site.

In the spirit of looking for obscure references to just about anything in Ulysses, I can find nothing else about laxatives or buckthorn (although a cad called Buck Mulligan does feature in the first chapter) and only one other reference to geese. Earlier in Ulysses, Stephen Dadalus imagines a drowned man and reflects that 'god becomes fish becomes man becomes banacle goose becomes featherbed mountain'. Make of that what you will - many have.

Images: The sketch of Leopold Bloom at the top of this post is by James Joyce, from Out of Print site.

*Occasional posts are called Plant Portraits (in brackets after the blog title and marked with an asterisk). These are usually about things other than, but including at least passing reference to, plants. Often they will be inspired by a book or something else in my cultural life. The idea is borrowed (very loosely and with due deference) from Milan Kundera's 'Novels, Existential Soundings', in his Encounters. These essays were as much, or more, about things other than the book being reviewed.