ESSEX   BOTANY   AND   MYCOLOGY  GROUPS 

             Odontites jaubertianus  susbsp. jaubertianus French Bartsia                                      new to Britain & Essex

                                       Scroll down for full paper from Essex Naturalist 2008

This bright yellow Bartsia  is not Parentucellia viscosa, the Yellow Bartsia, but a true Odontites very similar but for the colour to our Common Bartsia, Odontites vernus, with pinkish-red flowers. There is another one, just to confuse us, Odontites lutea which occurs in France but does not seem to have occurred over here yet.  

O. jaubertianus has been present in the Aldermaston/Greenham Common area in Berkshire since the 1930’s and has recently turned up on an old WW2 airfield in Northants.

Last year (September 2006) it appeared in some quantity in herb rich calcareous grassland amongst a colony of O. vernus on the site of the old WW2 Gosfield airfield where it was discovered by Diane Hulkes. We could not see any sign of it this year. The legacy of Spitfires with muddy wheels that landed in France towards the end of the war?

Essex Naturalist: 25 (New Series) 2008. 50-52.

        French Bartsia, Odontites jaubertianus (Boreau) D. Dietr. ex Walp. 

                                                    new to Essex.

KEN ADAMS

63 Wroths Path, Baldwins Hill, Loughton IG10 1SH

Abstract

This yellow-flowered Bartsia has now turned up in association with three different world war II airfields in southern England, suggesting that it may have been introduced by aircraft using continental airfields during the war. The latest discovery being found on the site of the disused Gosfield airfield in Essex. Our plant would appear to be the subspecies jaubertianus sensu stricto, rather than the subspecies chrysanthus (Boreau.) P. Fourn. reported from the other two U.K. sites.

In September  2006 I was approached by Diana Hulkes of Fisher’s Farm Beazley End, with a photograph (taken by Valerie Cutts) and specimen of a yellow-flowered Bartsia that had appeared on the edge of the site of the former Gosfield airfield, Adrian Knowles having suggested from the photograph that it was probably French Bartsia, Odontites jaubertianus. The plants formed a patch several meters long by a path just west of a hedge, in rough calcareous grassland amongst Wild Carrot Daucus carota, and our common red-flowered Bartsia, Odontites verna. Consultation of Flora Europaea and that fabulous illustrated Flore descriptive et Illustrée de la France by L’Abbé Coste, published in 1937, (but still better than anything we have! and covering 4354 species!) – established that there are nine annual,  yellow-flowered Bartsias on the continent in the genus Odontites, - not to be confused with the Yellow Bartsia, Parentucellia viscosa that occurs widely in damp sites in western and northern Britain and has occurred as a casual a couple of times in Essex.

Both Parentucellia and Odontites are members of the family Scrophulariaceae and are closely related to Euphrasia (Eyebrights), Melampyrum (Cow-wheats) and Rhinanthus (Yellow-rattles). They are all hemi- or semi-parasites, that is, they can obtain nutrition by forming haustoria (absorptive junctions) with the roots of other plant species in addition to being able to photosynthetise themselves. Parentucellia has smooth seeds, (with a fine reticulate pattern) smaller at c.0.5mm than those of Odontites which has seeds that exceed 1mm and are longitudinally ridged. Not a very helpful distinction with just a photograph! – but both our European Parentucellia species are glandular-pubescent, and have wider conspicuously toothed leaves. Of the possible yellow-flowered species in the genus Odontites, our plant has crisped, simple, pointed, appressed hairs, but no glandular hairs, so that rules out Parentucellia, O. viscosa and O. glutinosa. Its leaves are too narrow for O. lanceolata (need to be 4-10mm), its corolla tube considerably exceeds the calyx – knocks out O. tenuifolia; the corolla is less than 9mm so that knocks out O. longiflora and O. glutinosa (latter also glandular hairy) – and leaves us with  O. lutea and O. jaubertianus.

O. lutea, Yellow Odontites is widespread in Europe, extending to north-central France, southern Germany and eastwards to south central Russia, and one might therefore expect it as a casual over here. O. jaubertianus on the other hand is a French endemic calcicole, with a restricted distribution across central and southern France, and has variously been divided into three separate species/sub-species. The distinction between these two is not that easy. Both have flowers that consist of a long corolla tube divided apically into 4 lobes, an upper hooded lobe forming the upper lip, and two entire laterals plus an entire or slightly emarginated central lobe forming the lower lip. The key distinction given in the floras is that in O. jaubertianus the stamens are +  included under the upper lip, whereas in O. lutea they are widely exerted. However in our plants (and those from Northants.) the stamens are exerted. Looking at photographs of the two kinds of flowers however, it is possible to see what is meant. In O. lutea the stamens stick out as a bunch straight from the centre of the flower, whereas those of O. jaubertianus tend to hug the corolla lobes. The anthers are supposed to be yellow but both species have anthers that rapidly take on a pinkish-orange hue as soon as they dehisce. A rather better character for separating the two is in the comparative shape of the lobes of the lips. From photographs on the web, and the drawings in Coste, it is obvious that in O.lutea the lateral lobes and the lower lip are similarly reflexed outwards forming a hollow cone, whereas in O. jaubertianus both the lateral lobes and in particular the lower lobe are curved upwards and inwards so that the lower lip forms a cup-like structure and the upper lip is also slightly more hooded and less erect (see photograph from pressed flowers of our plant). Furthermore the ripe capsule in O. lutea is much longer than the calyx which has equilateral triangular teeth, whereas in O. jaubertianus the capsule is shorter than the calyx teeth, which are proportionately longer (as in our plant).

Thus our Essex plant is clearly O. jaubertianus, rather than O. lutea. Now it remains to establish which of the three subspecies it fits, if any. Subspecies cebennensis (H.J.Coste & Soulie) P.Fourn. is a local endemic of rocky slopes at one location in the Department of Aveyron in southern France, it has glandular-pubescent leaves and purplish anthers. Ours is clearly not this subspecies – but it is interesting to note that it does not key out in Flora Europaea because it is nested with forms that are eglandular! O. jaubertianus sensu lato has been reliably recorded from 19 of the 96 French departments, and reported from a further 4. So far (tela-botanica electronic flora) subspecies jaubertianus has been confirmed from 10 departments and subspecies chrysanthus from 8, in more or less the same area, a band across central France. Looking at the descriptions, subsp. jaubertianus should have long widely-spreading branches, leaves with plain margins, and the calyx teeth should only be one third of the length of the calyx. All characters that fit our Essex plant. Subspecies chrysanthus on the other hand should have short, semi-erect branching, leaves and bracts with 1-2 teeth, and the calyx teeth should be about half the length of the calyx. The latter is supposed to have golden-yellow flowers, whereas the residual subspecies can have cream flowers tinged with pink or ochre-yellow flowers (which would fit our plant).

The oldest known O. jaubertianus population in the U.K. was first found on a gravelly heath at AWRE Aldermaston, Berkshire in 1965. It was abundant in the 1960s but was down to 16 plants in 1988 and just one at a nearby site in 1983. It was also seen between 1970 and 1976 in a layby on Burys Bank Road by Bowden House north of Greenham Common, but has not been seen since (Crawley 2005). The only other known population was found in 2005 by Rob Mileto on an ex- WW2 airfield, Spanhoe, in Wakerley parish, Northants. Where a couple of dozen plants occur well spaced out on a thin layer of soil, in open rabbit grazed grassland, amongst Odontites verna, and not far from a patch of Autumn Gentian. Just like our plant they flower in early September just when O. verna is beginning to go over. The Berkshire pants have been determined by Eric Clement as subspecies chrysanthus. A photograph of the Spanhoe plant shows it to have leaves and bracts with several teeth, and calyx teeth extending to half way down the calyx. The branches also look erect rather than spreading. Thus it would appear that the Spanhoe plant is also subsp. chrysanthus.

Rob Wilson, who kindly provided the information on the Northants. population, suggests that our two sites may be long standing and may not have been noticed before because of the late flowering time. He also informs me that Spanhoe was used towards the end of the war by converted Liberator bombers to fly fuel to forward airfields on the continent. Thus planes could have landed in central France, been parked on the grass, and brought seed back on their tyres. A similar scenario could have applied to Gosfield, resulting in an independent introduction of the other widespread subspecies. Unfortunately none of us managed to visit the Gosfield site in 2007 or 2008 at the right time to catch our plant flowering, and once it’s over its virtually impossible to distinguish from O.verna. Better luck next year?

Acknowledgments

I am grateful to Diana Hulkez for alerting me to the occurrence of this plant and to Rob Wilson for information about the Spanhoe population.

References

CRAWLEY,M.J.(2005) Berkshire & South Oxfordshire Rare Plant Register.

www.bsbi.org.uk/Berkshire/Rare_Plant_Register_2005.pdf                             

L’ Abbé COSTE, H. (1906 & 1937) Flore descriptive et Illustrée de la France, Vol:3.. Paris.

TUTIN, T. G. et al. (1972) Flora Europaea, Vol: 3. Cambridge University Press.

TELA-BOTANICA (French Electronic Flora) http://www.tela-botanica.org/eflore

Captions: [see button at top for colour plates]

French Bartsia, Odontites jaubertianus, Gosfield  airfield. September 2006. © Valerie Cutts – note the spreading branches typical of subsp. jaubertianus.

Pressed specimen of French Bartsia from Gosfield, showing the entire leaves and bracts, and the short calyx teeth characteristic of subsp. jaubertianus sensu stricto © Ken Adams.