Dandelion clocks objects of great natural beauty
THERE are lots of Dandelion clocks around at present and they are objects of great natural beauty, design and perfection.
The first attractive quality of the Dandelion clock is its downsoft, puffy, see-through roundness, its near-perfect spherical shape. If the ball-shaped head doesn’t fall apart when you break off its supporting stem, it’s worth picking a clock and examining its structure more closely.
The clock is, of course, the reproductive seed-head that develops from the familiar yellow flower. If you blow gently the clock fractures and reveals its component parts. The round head is composed entirely of the plant’s fruits each borne at the end of a stalk topped with a feathery parachute.
Each dark, cylindrical fruit is long and narrow like a tiny cucumber and is inserted into the swollen top of the stem that formerly bore the flower.
When the seed-head is ripe a gentle breeze is all that is needed to toss the stem and tug the fruit free from its base. Once free, the fruit is borne aloft by the breeze and floats away on its feathery appendage before its weight parachutes it to the ground.
The biological advantage of the Dandelion clock is that it uses the wind to disperse the plant’s seeds far and wide away from parent plant. The great abundance of Dandelions is testimony to the effectiveness of the dispersal mechanism.
The seed -head is known as a ‘ clock’ because, in the past, children blew at the fluffy head and imagined they were telling the time by counting how many puffs it took to blow all the fruits away. Each puff was equivalent to one hour. Needless to say, the erstwhile technique wasn’t as accurate as a modern-day mobile ‘phone but it was probably more innocent fun.
Each airborne fruit floating on its tiny parachute contains a single seed. The word ‘fruit’ often conjures up images of soft, sweet, juicy things like blackberries or plums. However, in addition to the juicy fruits there are dry ones like the Dandelion with its hard, papery-walled fruits.
Juicy fruits have evolved to attract animals and birds to eat them thereby carrying the seeds away in their intestines to be deposited at a later date somewhere far from the parent plant.
Dandelion fruits are dry and papery as they use the wind to carry there offspring away from the parents. They have no need to be sweet or juicy.
are common in some breeds of dog. Flat- Coated Retrievers, Golden Retrievers, Irish Wolfhounds and Labrador Retrievers are affected, with cancer dramatically shortening the average lifespan of some breeds e.g. over 50% of Flat- Coated Retrievers die of cancer, and the average age of this breed is only eight years. For researchers, identifying the specific genetic causes of inherited types of cancer is a key goal. If the specific genes linked to the cancers can be identified, these can be removed by screening the population before breeding from dogs, only breeding from those that do not have the offending gene. This is a very active area of current research.
is more difficult to prevent: there’s a long, long list of known and possible causes of cancer but there are some specific ones that pet owners should know about.
Ultraviolet radiation from sunlight causes malignant squamous cell carcinoma of the ear tips and nose of white cats, because they have no pigment to protect them from the sun. Regular application of sun block to white cats’ ears and nose tips prevents this type of cancer.
Viruses can cause cancer and vaccines can sometimes protect against these, preventing specific cancers. Feline Leukaemia Virus, causing leukaemia in cats, is the best example in pets.
Hormones can have a strong effect on cancer. Repeated exposure of mammary tissue to high levels of oestrogen predisposes to cancer: if a bitch is spayed before her first season, the risk of cancer is reduced by 99.5%. In cats, spaying at any age reduces the risk of mammary tumors by 40% to 60%.
In contrast, early spay/neutering of giant breeds of dog is linked to an increased incidence of osteosarcoma (bone cancer), so it is now recommended to leave these breeds until sexual maturity before doing the operations (e.g. 18 months of age).
Nowadays, vets say that a decision on spay/neuter should be done on an individual
Acquired cancer