Tuesday, 18 September 2012

Wednesday wildflower: dove's foot cranesbill

I love the quaint English names a lot of our weeds have; this week's is a beauty.  Cranesbill as a common name for the genus Geranium is a reference to the elongated styles on the fruits; dove's foot refers to the leaf of this species.
Geranium molle, Raroa Road, Highbury, Wellington
There's another common name mix-up around geranium: the garden geraniums are classified botanically in the genus Pelargonium, although some true geraniums are also cultivated.
Geranium molle flowers, Highbury.
Dove's foot cranesbill is widespread in its native range of Eurasia and North Africa, and it's widespread in New Zealand too (Webb et al. 1988) and other parts of the world like the USA. It is distinguished from other species by its spreading sepals (C below), the short claw (narrowing at the base) of the petals (E below), and the hairless and wrinkled mericarps (1-seeded partitions of the fruit, F below).  The individual inflorescences are leaf-opposed (A below), which indicates the inflorescence is actually terminal and the new continuing stem arises from its axillary bud.
Geranium molle. A, stem and upper leaves; B, stem hairs; C, young flower; D, older flower, E, petals showing the short claw, underside at left; F, mericarps; G, flower after pollination and petal fall; H, basal leaf, abaxial surface; I, basal leaf, adaxial surface; J, stem leaf, abaxial surface; K, stem leaf, adaxial surface; L, ripe mericarps; M, unripe mericarps.
Geranium is quite a large genus in New Zealand.  The database mantained by the taxonomists at New Zealand's largest plant collection, Landcare Research, records 7 native and 14 naturalised or casual species, to which the NZ Plant Conservation Network database adds G. incanum (naturalised).  Webb et al. (1988) recorded 7 native and 8 naturalised.  The increase partly results from new taxonomic revisions that have promoted some varieties to species rank, new introductions, and perhaps a widening of the criteria for what is considered naturalised and casual.

Cranesbills have a link with famous British scientist John Dalton.  Dalton was colourblind, suffering a condition now sometimes known as Daltonism, and reported that the colour of cranesbill flowers was sky blue.  When others disagreed, he realised he wasn't seeing colour as they did.  He left his eyes to science, and genetic analysis has shown he lacked a functional copy one of the three opsin genes that are needed for full human colour vision.


Webb, C.J.; Sykes, W.R.; Garnock-Jones, P.J. 1988.  Flora of New Zealand Vol. 4.  DSIR, Christchurch.

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