As we move through the colder months of the year, a hidden world of nature is being revealed to us. Leaves and flowers fall away, exposing the skeletal structures beneath. Along the banks of our chalk streams, we can see strange shapes that were previously cloaked in clouds of small white flowers: the dry remains of plants in the Apiaceae or Umbelliferae family, more commonly known as umbellifers.

This plant family is very large and contains many poisonous species, but also edible ones like carrot, celery, parsnip, fennel, cumin, dill, and coriander. If you’re thinking that its name sounds rather like “umbrella”, then you’re spot on: the two words share a common root in the Latin word "umbra", which means shade or shadow. The umbellifer family itself is named for a common feature of its members: umbels, which are flower clusters that radiate out from a main stem.

In most umbellifer species, these flowers are white or cream, and bloom throughout the spring and summer. They usually decline as the weather grows cooler, leaving only their dried-out stems behind. But even in wintertime, umbellifers are of great value to wildlife - they provide cover when other vegetation is sparse, and some insects take shelter inside their hollow stems. Let’s look at some of the river-loving members of this floral family!

If you’re familiar with Hampshire’s history, you’ll know that watercress growing has been an important local industry for centuries. But this peppery plant also grows wild at the edges of our chalk streams, and can often be found alongside our first umbellifer: fool’s watercress. This creeping perennial loves stream margins and wet ditches, although it can also be found in wetlands. Unlike watercress – which is actually in the cabbage family – it smells like carrot when crushed underfoot.

A similar-looking species is lesser water-parsnip, which grows on damp ground or in the shallow edges of clear, flowing water, making it an ideal plant for chalk streams. Because it spreads via stems that run over the ground, called “stolons”, it can play a key role in reducing riverbank erosion by holding the soil together. One way to identify this plant is by looking for a pale ring at the points where leaves branch off from the stem. True to its name, walking on it releases the scent of parsnip.

​​Our riverbanks are also home to hemlock water-dropwort (Oenanthe crocata), which is not to be confused with the more famous "poison" hemlock (Conium maculatum), although both are toxic and grow near water. The former's close relative, river water-dropwort (Oenanthe fluviatilis), is a little more specialised; it likes clean, lowland rivers with plenty of calcium. This makes our chalk streams fantastic habitats for this species, providing they’re in a healthy condition.

Pictured below from left to right (click to expand): Fool's watercress / Lesser water-parsnip / Hemlock water-dropwort / River water-dropwort.

Because many of the umbellifers look alike, caution is advisable when you're around them. Several species are highly toxic if eaten - including to dogs and livestock - while some have sap that can cause skin irritation. Giant hogweed in particular can cause painful, recurring, photosensitive blisters after only brief contact. This invasive species can reach a towering 5m when fully grown, but is harder to identify in its younger stages. So if you're in any doubt about which plant you've found, it’s best to admire it from a distance.

We're improving the health of seven beautiful Hampshire chalk streams, as part of the Watercress and Winterbournes scheme. Explore our work to learn more about these globally rare and ecologically precious habitats!

About Watercress and Winterbournes