Sunday, 11 March 2012


I saw this while I was walking home through Kelburn last week (just where the mobile library pulls in on Upland Road, if you're local).  Chicory, Cichorium intybus, is a member of the sunflower family Asteraceae, and it gives its name to a distinctive subfamily of that family, the Cichorioideae.  Within Cichorioideae it belongs in the lettuce tribe, Lactuceae.

Lactuceae are distinguished by having just one type of floret in their heads (what looks like a flower in this family is really a cluster of tiny florets), and these are called ligulate florets.  Each floret has five petals joined into a tube and then split down one side to form a flat strap with five teeth at the tip.  In the centre is a style with two stigmas, surrounded by a tube of five anthers (dark blue in the photo above).

Chicory is used as a livestock food in New Zealand and sometimes escapes onto waste land.  The roots are sometimes roasted and ground as a coffee substitute.

Other members of the tribe are dandelion, lettuce, catsear, sow thistle (puha), and that serious pest in New Zealand, Hieracium.  Nearly all of them have yellow florets, but a few have orange or purple.  The sky blue florets of chicory are very unusual.
Native dandelion, Taraxacum magellanicum, flowers, Remarkables Range, Otago.
Native dandelion, Taraxacum magellanicum, fruits, Remarkables Range, Otago.
Catsear, Hypochaeris radicata.
Hieracium lepidulum is a serious weed in Otago and Canterbury.
A capitulum (flower head) of Hieracium lepidulum.
Orange hawkweed, Hieracium aurantiacum.

Apart from having all ligulate florets in their capitula, another thing the species in this tribe have in common is milky juice or latex.  The juice is rich in sesquiterpene lactones, which give it a bitter taste and probably deter grazers.  That's why lettuce are sometimes bitter.  Dandelion is a diuretic, with explains its common name in France, piss-en-lit.

Botanically, the best known member of the family is Tragopogon, goat's beard or vegetable oyster.  T. porrifolius is a minor vegetable, but the genus's fame results from its role in evolution research.  American botanist Marion Ownbey discovered that three introduced European species of Tragopogon had hybridised in America to make two new hybrid species.  These are the classical examples of an evolutionary process called allopolyploidy, where a sterile hybrid doubles its chromosome number, restoring fertility and making an instant new species.  It's a common process in plants, but Tragopogon is the best known example.  One surprising thing is that it's happened more than once.  Lately the genetics of allopolyploidy in Tragopogon have been studied in great detail by a team led by Doug & Pam Soltis in Florida.  Jennifer Tate and Vaughan Symonds, now at Massey University, were part of a team that duplicated this process in culture.  The three parent species, T. porrifolius, T. dubius, and T. pratensis, all occur in New Zealand, so one day we might find it has happened here as well.

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