Flower is one of the earliest words we learn, and a fundamental part of our every day lives. Flowers may be the most common form of nature we encounter on a day-to-day basis, and yet when we try, they are surprisingly hard to define. We posted the question on the BBC Earth Facebook page to see if any of our readers had the answer.
Stewart McPherson is prepared to go a long way for his science: even into the grounds of a prison in the Philippines. "I had to be guided by murderers," he says. His target was, appropriately enough, a plant that kills: a tropical pitcher plant called Nepenthes deaniana that traps and digests insects. "It hadn't been seen for nearly 100 years."
It has been getting a little warm lately. In November 2015, Brits experienced the hottest November days ever recorded in the UK. That was shortly followed by news from the World Meteorological Organization that 2015 is likely to be the hottest year since records began.
In 1981, mountain gorillas were at rock-bottom. Confined to a small mountain range in central Africa, with humans encroaching on their habitat bringing poaching and civil war, their population was estimated at just 254. They would all have fitted into a single Boeing 747.
Today things look a little better. A survey in 2012 reported that the population was up to 880. That is a big improvement, but it's still only two Boeing 747s of mountain gorillas. They remain critically endangered.
Evolution is one of the greatest theories in all of science. It sets out to explain life: specifically, how the first simple life gave rise to all the huge diversity we see today, from bacteria to oak trees to blue whales. For scientists, evolution is a fact. We know that life evolved with the same certainty that we know the Earth is roughly spherical, that gravity keeps us on it, and that wasps at a picnic are annoying.