Source: Knapp, Alan, and Frances Abraham. “Lotus angustissimus and Lotus subbiflorus in Sussex.” Sussex Botanical Recording Society Newsletter, no. 65 (January 2008). http://sussexflora.org.uk/wp-content/uploads/2016/03/Newsletter_Jan_2008.pdf.
While recording for the new Flora of Sussex several species thought extinct in the county have been refound, but few have been as unexpected as the discoveries during Summer 2007 of Lotus angustissimus (Slender Bird’s-foot-trefoil) for the first time in over 70 years and of Lotus subbiflorus (Hairy Bird’s-foot-trefoil) for the first time ever in Sussex.
In East Sussex Lotus angustissimus was first found in 1798 among rocks near Hastings (also the first British record) and it was subsequently recorded at one or two other coastal sites in the Hastings area. It was last reported in 1932 but, in his Flora of Sussex (1937), Wolley-Dod considered that ‘in the absence of a specimen it is safer to regard it as extinct at Hastings’. He also dismissed the only two records from West Sussex: at Pagham (‘requires confirmation’) and Worthing (‘probably a casual…very doubtful’).
In June 2007 several plants of L. angustissimus were found by FA in a patch of about 1m x 0.5m in a sandy field near Fittleworth in West Sussex, and a second patch was found when FA & AGK revisited the same field a few weeks later. The field has been much visited by botanists over the years because it adjoins a small area of sandy grassland with a rich flora which includes Filago vulgaris (Common Cudweed), F. minima (Small Cudweed), F. lutescens (Red-tipped Cudweed) and many other species of interest. The field itself has at various times been used for keeping pigs and cultivated for maize and other cereals. However, it has been fallow and apparently unmanaged for several years and has itself acquired a rich flora, including the three Filago species and Apera spica-venti (Loose Silky-bent), as well as Amsinckia micrantha (Fiddleneck), Ornithopus perpusillus (Bird’s-foot), Trifolium arvense (Hare’s-foot Clover), T. campestre (Hop Trefoil), Scleranthus annuus (Annual Knawel), Spergula arvensis (Corn Spurrey) and Spergularia rubra (Sand Spurrey). The species most closely associated with the Lotus plants were Conyza canadensis (Canadian Fleabane), Filago vulgaris, Holcus lanatus (Yorkshire-fog), Lolium perenne(Perennial Rye-grass) and Tripleurospermum inodorum (Scentless Mayweed).
A few weeks later FA found a further colony of L. angustissimus on the margin of a sandy field about 400m from the first. In the past this field too has been used for pigs and various crops, but has been uncultivated for several years. Unlike the first field, it has been sown with rye grass and clover, but wide and sparsely vegetated margins support a flora similar to that of the first site, although less rich and lacking most of the rarities.
On September 2nd Dawn Nelson led an SBRS field meeting to record a farm west of Rogate, very close to the Sussex/Hampshire border. The farm is “pick your own” and has a reputation for its asparagus crop. The soil is very sandy, and recording in the morning in the “pick your own” fields produced a range of interesting species including Amaranthus hybridus (Green Amaranth), Erodium moschatum (Musk Stork’s-bill), Festuca brevipila (Hard Fescue) and Geranium pusillum (Small-flowered Crane’s-bill). In the afternoon we moved on to record the margins of the asparagus fields and soon came across a small patch of a very hairy Lotus species with rather golden yellow flowers. After some discussion we realised that it must be Lotus subbiflorus and, as we continued around the field edge, more plants were found. While identifying the Lotus subbiflorus we noticed that the feature in the key in Stace (1997) describing the number of seeds in a pod did not apply. Stace states that the number of seeds in a pod should be no more than 12. While this was true in a few cases we found that most pods had 14 seeds and a few had up to 16 seeds.
As we walked further along the field edge a plant with paler yellow flowers was noticed among the L. subbiflorus. On careful examination this proved to be Lotus angustissimus. In the end we found that the colony of L. subbiflorus extended in patches for 100m along the field edges and contained well over 100 plants. Among these we found two large plants of Lotus angustissimus. All were growing in the edge of a rough grassy strip a few metres wide around the edge of the field with such species as Amaranthus hybridus, Artemisia vulgaris (Mugwort), Chenopodium album (Fathen), Cirsium arvense (Creeping Thistle), Dactylis glomerata (Cock’s-foot), Festuca brevipila, Stellaria graminea (Lesser Stitchwort) and Tripleurospermum inodorum. Searches of adjacent fields with asparagus crops failed to reveal any more colonies of either Lotus species, but this field had a further surprise in store. During a subsequent visit three plants of Scorpiurus muricatus (Caterpillar-plant), another new species for West Sussex, were found growing in the sandy edge of the field.
An obvious question is why these species have not been discovered in these areas of Sussex before. In the case of the L. subbiflorus site the number of plants present makes it unlikely that they would have been overlooked but, as far as we can tell, this particular area has not been well recorded in the recent past. The plants may therefore represent a native population which has been present but un-noticed for many years. However, the presence of the Mediterranean species Scorpiurus muricatus and of large numbers of Amaranthus hybridus in the same field raises the possibility that the Lotus species could be introductions here. The owners of the farm told us that, before planting the asparagus, they apply a mixture of chicken manure and composted garden waste from Hampshire, so it is conceivable that the Lotus subbiflorus originated from Hampshire.
The situation regarding the Fittleworth L. angustissimus is rather different. This site has been visited by many botanists but the plants here were in very small isolated patches, despite the fact that there are large areas of apparently suitable habitat all around. It is also possible that the plants only germinate occasionally and that conditions this year were especially favourable. We will certainly re-visit both sites in the next few years in order to see what happens to the populations of both species.
We would like to thank Dawn Nelson for arranging and leading the field meeting which led to the discovery of Lotus subbiflorus, and the sharp eyes of Kathryn Knapp who first noticed the Scorpiurus muricatus. We also thank the landowners of both sites.
(Edited version of a letter to be published in the BSBI Newsletter)