All around you can tell that standards are slipping.

Potholes in the road gradually become craters. Rubbish, carelessly discarded by the anti-social amongst us, is blown to gather in every corner or pecked at by crows and seagulls. Soon we will see that fields are yellow with uncontrolled, poisonous ragwort and Japanese Knotweed continues its invasion of our country relentlessly.

Our ditches too are neglected, filling with leaves and debris, so that localised flash flooding is more common. And this brings with it a health hazard to our dogs that previously was only a problem for cattle and horses.

Water hemlock is the most toxic plant in Britain. Properly called Oenanthe crocata, its name is derived from the Greek ainos (wine) and anthos (flower) because of the wine-like scent of the flowers.

The leaves, however, are reminiscent of celery or parsley. You will recognise the plant as it is grows in lowland areas close to wherever there is water. The leaves, which remain green in winter, are celery like, with the lower, spreading, triangular ones being about 30cm, and it has tall, white, umbrella patterned flowers about five to 10cm across, made up of 15 to 30 umbels.

Pretty though it may be, every part of water hemlock is poisonous but the most dangerous is hidden away below the earth’s surface. The roots are the deadliest component of this plant.

These are pale yellow, very similar to parsnip, and composed of five or more fleshy tubers, giving rise to the nickname Dead Man’s Fingers. They exude a yellowish liquid when cut, which will stain the skin. But here’s the rub. You can do anything to this plant and it remains every bit as nasty as before. You can cut it, you can squash it, you can chop it, you can jump up and down on it, and you can dry it. None of it reduces its harmful effects.

The toxic principles are cicutoxin and oenathetoxi; polyunsaturated alcohols that affect the nervous system.

Animals that ingest even tiny quantities (two bites of a tuber have killed humans) show salivation, dilated pupils, respiratory distress and convulsions. A horrible death from respiratory failure or seizures is common. Hitherto, only cattle and horses were likely to accidentally ingest the plant, most often after it had been cut and dried when diggers were working in fields.

And why it is becoming so dangerous to our dogs? Spreading through our wet ditches, it can be trampled by livestock and become unrecognisable. The toxins, however, remain active in stagnant water, just waiting for a thirsty German Shepherd to come along. Maybe a ditch does eventually get dug out, causing tubers to be left exposed, only for that happy, inquisitive Labrador to grab a bite.

Relentless rain, which we see so often, can stir things up considerably. Plants, which once were high and dry, can be concealed under water. Hemlock, disturbed by flooding and high winds has even turned up on our beeches.

Make sure you can recognise it. Google an image of it now, and keep it in mind.