View across the river Great Ouse to Passenham church with Common Club-rush prominent on the opposite bank and Tussock Grass dominating the meadow behind (Photo: Jenny Mercer)
Introduction
What’s that plant – and why?
On Sunday 11th August, 13 members of the MKNHS Plant Group gathered in and around the car park on Calverton Road on the edge of Stony Stratford for the third field visit of the group, this time a riverside setting along the Great Ouse. The Plant Group has been established this year to provide opportunities for Society’s members to become more confident about identifying plants, with good attendance at all three events. Previous visits to Shenley Wood and Stonepit Field had focused on woodland plants (on a very wet day in April) and a wildflower meadow on chalky soil (on a bright June day). This was the first visit to a riverine habitat.
Sunday 11th was a very warm summer’s morning, and the car park and river were full of runners, picnickers, wild swimmers and paddleboarders – and naturalists. There was also a family group by the riverside emptying their crayfish trap, transferring about 100 Red Signal Crayfish (a non-native, invasive species) to a large bucket for their lunch.
We were ably led by Charles Kessler and Di Parsons along on the riverbank, to see a profusion of reeds and rushes on both sides of the river, and other plants along the path and riverbank. It is a rich area botanically, and beautiful on a sunny morning, with views across the fields over the river to Passenham church.
So, what did we learn?
Waterside Plants
Improving identification of waterside plants was one of the key objectives of the Event. With this in mind, Plant Group members were provided in advance with a briefing note prepared by Charles Kessler on some riverside plants likely to be observed to highlight their key distinguishing features in recognition that very few flower identification guides include them. This, with a commentary from Charles in the field, was invaluable in identifying them. Six key species were observed, four being widely distributed along the water’s edge of the area we visited: Common Reed (Phragmites australis), a grass; Reed Sweet-grass (Glyceria maxima); Reedmace (Typha latifolia), a grass, which is nevertheless sometimes called Bulrush; and the tall dark green Common Club-rush (Schoenoplectus locustris), also sometimes called Bulrush, in this case, more correctly. The remaining two were more scattered: Reed Canary-grass (Phalris arundinacea) and Branched Bur-reed (Sparganium erectum), another grass. As the above shows, the categorization is complex, and not always reflected in the common names. We were reminded of our President’s very useful ditty in using the stem to differentiate grasses, sedges and rushes: ‘Sedges have edges, Rushes are round, Grasses have joints right down to the ground!’
Only two plants growing in open water were observed: Yellow Water Lily (Nuphar lutea) (no longer in flower) in the river and Common Water-star (Callitriche stagnalis) in the slow-moving mill stream and inlets.
Reed Sweet-grass (l) and Common Reed (r) compared; Branched Bur-reed
Riverbank Plants
The riverbanks vary in their height and profile so that the plant life is a mix of water-loving plants, and water-tolerant not limited to this habitat. Examples of the former include Water-forget-me-not (Myosotis scorpiodes), Water Mint (Mentha aquatica), Wild Angelica (Angelica sylvestris) and Marsh Woundwort (Stachys palustris). Wild Angelica is a tall stout plant with a hairless stem, unusual sheafs at the base of its stalks, and with a typical umbellifer (umbrella-shaped) florescence.
Wild Angelica
The latter category (water-tolerant, but not limited to this habitat), included Great Willow Herb (Epilobium hirsutum); Greater Burdock (Arctium lappa), where we learnt how to identify it from Lesser Burdock through the lower leaf stalks, the Greater being solid and the Lesser hollow; Water Dock (Rumex hydrolapathum); Greater Celandine (Chelidonium majus), a yellow cruciform flower of the poppy family quite unrelated to the better-known Lesser Celandine of early Spring; Soapwort (Saponaria officinalis), non-native, probably a garden escape; and Common (Stinging) Nettle (Urtica dioica). We spent some time examining the Common Nettle with a hand lens to distinguish the male and female flowers, each on separate plants.
Greater Celandine
There was not time to do full justice to the trees of the riverbank but Alder, and Poplar and Willow species dominate.
Want to know more?
If you want to know more, there is a Consolidated List of Plants Observed and Photo Album on the Plant Group website page, or link here . The photographs are linked to the species observed and several of them demonstrate identification features which are useful in the field when trying to differentiate between similar but different species.
Thanks
Thanks to Charles and Di for their co-leadership, to Charles for his waterside plants briefing note, to Bob Phillips for his excellent photographs, Jenny Mercer for her help with the production of the Consolidated List, and Martin Ferns for his editorial input and for helping to draft this Trip Report.
Joe Clinch
September 2024