Q&A

This month’s panel

BOTANY

Which flower had Darwin scratching his head?

Charles Darwin travelled the world, but also spent countless hours observing nature in Britain (see p12). One common wildflower in his garden and local woods long perplexed him. Why did primroses appear in two quite different forms? So-called ‘pin’ types had a long style (the stalk-like female part of the flower) but short, hidden stamens (the pollen-bearing male part of the flower). ‘Thrum’ versions had a short, hidden style, but long, prominent stamens. Darwin spent years painstakingly collecting, marking and experimenting with pollen and seeds from hundreds of primroses, and found that the two forms had different pollen. They could not self-pollinate, thus helping to achieve cross-pollination. Darwin described this as “One of the most surprising facts I have ever observed,” adding that “No little discovery of mine ever gave me so much pleasure.” Alex Morss

REPTILES

Are any snakes poisonous?

Many people call a snake ‘poisonous’ when they mean ‘venomous’. The latter involves injecting prey with a toxin (venom), whereas the former is secreting a defensive toxin (poison) that an attacker would prefer not to touch. Just