Ben Locke

(Some of these notes first appeared in the members only Gloucestershire Naturalists’ Society Facebook Group, GNS Playground, on 5 July 2019).

There are three water-dropworts (Oenanthe species) commonly found in the floodplain meadows of the Severn and Avon in Gloucestershire. They are difficult to tell apart, especially when the basal leaves have disappeared, which often will have happened by mid-June.

They have slightly different habitats and time of flowering, but this can’t be relied on. At the wettest end, in places where water lies all winter or the edge of a pond, is Tubular Water-dropwort (Oenanthe fistulosa). This tends to be the latest to come into flower, often in early July. Its characters include a very reduced number of partial umbels – sometimes just two or three, the stem is constricted at the nodes, and the upper stem leaves are very reduced – a bit like a stick drawing of a leaf. Narrow-leaved Water-dropwort (Oenanthe silaifolia) is the plant of the wet meadows and is the earliest to come into flower, often in mid-May. In the driest fields on the floodplain and unimproved fields and road verges off the floodplain, is Corky-fruited Water-dropwort (Oenanthe pimpinelloides) which flowers from about mid June.

It is easy enough to decide which of the the latter two you have if you are comparing them side-by-side, but when you only have one plant in front of you you can begin to doubt yourself. These notes may be helpful.

A consistent character is the stem at the base of the flowering shoot. If it squashes easily between the thumb and forefinger it is O silaifolia. The stem here is fairly silky to the feel and only gently ridged. If it gives very little when squashed between the thumb and forefinger and feels hard and ridgy, it is O pimpinelloides.
At the other end of the plant, looking at the biggest head of flowers, if you can imagine getting your fingers between them then it is silaifolia. If in the biggest head of flowers the partial umbels are touching or almost touching then it is probably pimp. This character is even better developed as the fruits ripen.
A clincher difference between these two – in silaifolia the fruits of the partial umbel splay out into a gentle dome. In pimp they stay pretty much upright, so that looking from the side you can see a row of individual fruits in profile.

Juliet Bailey
21 June 2021

The earliest grass to flower in quantity in the Gloucestershire meadows is Meadow Foxtail (Alopecurus pratensis) sometimes joined by Sweet Vernal Grass (Anthoxanthum odoratum).

Meadow Foxtail is the first thing to poke up its head above the general level of the sward, and the dense waving flowering heads in May, can give the meadows a dark shimmering haze at about knee height.

In the meadow photo, Meadow Foxtail is the one waving its heads in the clouds, with Sweet Vernal the main grass flowering in the lower storey. The buttercup is Bulbous Buttercup, also an early flowerer.

Up close, the reason for the name Foxtail is obvious, and the flowerhead can be seen to be packed quite densely and neatly usually into a parallel-sided cylinder. Sweet Vernal can have the same overall shape but is looser and tattier. Sweet Vernal is a much shorter grass – usually only up to mid-calf height.

Get really close, with good eyesight or the help of a hand lens, and the individual components making up the flowering head look very different. From the photos with the pulled-apart heads, it can be seen that the spikelets of Sweet Vernal are lopsided, and they are on short stalks up to about 1mm long joining to the main stem. The spikelets of Meadow Foxtail are flattened but elegant and almost symmetrical, joining the main stem with virtually no stalk.

Fun Facts:

• When in doubt, chew it!
  Pull a grass stem so that the lower part of the stem comes out clean from its sheath. Chew it. Wait a few seconds and see what taste sensation you get. Meadow Foxtail is pleasant enough, but nothing special. Sweet Vernal has a rich sweet perfume – the scent of “new mown hay” due to the chemical coumarin. Hence the name – Sweet because it is sweet, and Vernal which means spring-time.
• In the past, both grasses have been sown by farmers, Meadow Foxtail has early growth, good yield and stock find it highly palatable. However, it takes several years to establish well so isn’t suitable for modern requirements in a temporary grass field. Sweet Vernal was widely sown because of its fragrance but is no longer considered an agricultural grass as it does not produce much matter and is rather stemmy. Apparently, stock don’t like it much.

Juliet Bailey
May 2021

Find a meadow with a lot of Meadowsweet (Filipendula ulmaria) and Great Burnet (Sanguisorba officinalis) and you have hit botanical gold. These are the key species that shout “floodplain grassland of good quality” in Gloucestershire. Sure, you’d hope to find other indicator species as well, but these get you off to a flying start.

They are easy enough to identify in summer when they are tall plants in full bloom but surveyors should become familiar with what they look like earlier in the year, in April and May, when they are just ankle-height leaves.

The photo with the 10cm ruler shows one leaf of Meadowsweet on the left and one leaf of Great Burnet on the right. They are compound leaves, so the separate green portions are all just leaflets of a single leaf.

These two species often grow together, and in spring you might need to look carefully to decide which you have.

The Meadowsweet leaf is coarser with pleated leaflets and the parallel side-veins on the leaflets showing clearly.

The Great Burnet leaflets may be folded in half, but won’t show the concertina folding. The leaflets are often heart-shaped and attach to the main leaf stem via a bare stalk. The veins are not nearly so obvious.

Both can have quite a lot of red pigmentation on the leaf stem and leaflets when young. Great Burnet leaflets in particular can look almost silver when they catch the light.

Fun fact:
Meadowsweet was one of the mediaeval strewing herbs that were scattered on the
floor of the halls. This wasn’t particularly the flowers, which are foamy and white
and have a honey smell, but the leaves and stems which have a pleasant but strong
odour of ripe cucumber with maybe a nip of antiseptic. Great Burnet leaves also
smell of cucumber, but to me it is a less complex scent, perhaps like under-ripe
cucumber skin.

Juliet Bailey