A SHORT NOTE ON THE OCCURRENCE OF SORBUS MOUGEOTII IN THE SPANISH PYRENEES

1. Introduction

While on a trip to the Spanish Pyrenees in July 2017 I found a whitebeam that resembled Sorbus mougeotii. This short note describes the locations and morphology of the specimens I found and discusses their identity in the context of Spanish and UK Sorbus descriptions. Both specimens described below were shrubs rather than trees as they had multiple stems growing from the base of the plants. The presence of S. mougeotii in Spain is not agreed amongst others who have studied Sorbus in this country. The account of Sorbus in Flora Iberica (Aedo and Aldasoro, 1999Aedo, C. & Aldasoro, J.J., 1999. Sorbus in Castroviejo, S. (Coord.) Flora Iberica 6: 414-429. Real Jardín Botánico de Madrid-C.S.I.C. Madrid.) only includes S. intermedia. S. mougeotii is given as a synonym. S. mougeotii is recorded as occurring in the Pyrenees by Flora Europaea (Warburg & Kárpáti 1968Warburg, E.F. & Karpati, Z.E., 1968. Sorbus. In Tutin, T.G., Heywood, V.H., Burges, N.A., Moore, D.M., Valentine, D.M., Walters, S.M., Webb, D. A. (eds) Flora Europaea 2: 67-71 pp. Cambridge University Press, Cambridge.), while S. intermedia is not listed as occurring in Spain, but this conflict is not referred to in the Flora Iberica text about S. intermedia. Oria de Rueda Salgueiro et al. (2006)Oria de Rueda Salgueiro, J.A., Martínez de Azagra Paredes, A. & Álvarez Nieto, A., 2006. Botánica forestal del género Sorbus en España. Investigación Agraria: Sistemas y recursos forestales, 15(S1): 166-186. follow Flora Europaea and regard S. intermedia as a northern European species, which is replaced by S. mougeotii in Spain. The European and Mediterranean plant database (Kurtto, 2009Kurtto, A., 2009. Rosaceae (pro parte majore). In: Euro+Med Plantbase - the information resource for Euro-Mediterranean plant diversity. Published on the Internet at http://ww2.bgbm.org/EuroPlusMed/ [accessed 1/9/2018].) also includes Spain in the distribution of Sorbus mougeotii, but labels S. intermedia as “native: reported in error”.

2. Site descriptions and photographs of each specimen

The approximate location is given for each specimen using vertical aerial images on Google Earth (version 7.3, 2017)Google Earth 7.3, 2017. Vertical aerial images of Hecho and Aísa valleys, Spanish Pyrenees, dated 2015. Published on the Internet at http://www.google.com/earth [accessed 30/07/2017]. , although it should be noted that these locations and their dependent altitudes were estimated after the trip. Google Earth is aligned to the World Geodetic System 1984.

2.1. Hecho valley

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The valley was visited on 10^th July 2017. The Sorbus shrub was growing on the south side of the track which ran up the Hecho valley (Figure 1 & 2), beyond the section open to traffic. It was on the slope about 2-3 metres above the track. The track itself was part way up the southern slope of the valley, well above the river in the valley bottom. A few other similar Sorbus individuals were also seen along the sides of the track.

Location to 500 m precision: Latitude 42⁰ 51’ 10.31” N, Longitude 0⁰ 41’ 45.90” W. Altitude: 1256 m.

Figure 1.  Whorl of leaves on a side branch of the Hecho valley specimen

Figura 1.  Verticilo de hojas en una rama lateral del ejemplar del valle de Hecho

Figure 2.  A cluster of fruit on the Hecho valley specimen. The largest fruit touches the ruler between the 7 and 8 centimetre marks on the ruler. Lenticels on the fruits were few and small.

Figura 2.  Un racimo de frutos en el ejemplar del valle de Hecho. El fruto más grande alcanza entre 7 y 8 centímetros. Las lenticelas de los frutos eran escasas y pequeñas.

2.2. Aísa valley

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The valley was visited on 11^th July 2017. The Sorbus shrub (Figure 3 & 4) was growing on the east side of a track which ran south from a picnic area and car park. The site was in the valley bottom, close to the river. The site was much more sheltered than the Hecho site. Other individuals of what appear to be the same Sorbus to the one photographed were quite frequent in the surrounding open woodland.

Location to 100 m precision: Latitude 42⁰ 43’ 54.85” N Longitude 0⁰ 35’ 39.10” W. Altitude: 1375 m.

Figure 3.  Whorl of leaves on a side branch of the Aísa valley specimen

Figura 3.  Espiral de hojas en una rama lateral del ejemplar del valle de Aísa

Figura 3.  Fruits on the Aísa valley specimen. Lenticels on the fruits were few and small.

Figura 3.  Frutos en el ejemplar del valle de Aísa. Las lenticelas de los frutos eran escasas y pequeñas.

3. Leaf and fruit measurements

Some measurements were made of leaves and fruit (Table 1), as quantitative information is of importance in identification of Sorbus (Rich et al., 2010Rich, T.C.G., Houston, L., Robertson, A., & Proctor, M.C.F., 2010. Whitebeams, Rowans and Service Trees of Britain and Ireland. A monograph of British and Irish Sorbus L. B.S.B.I. Handbook No. 14. Botanical Society of the British Isles, London.). Only a small amount of data was collected due to time constraints. Direct leaf length measurements were made with a ruler in the field, other data were derived from the photos. Only leaves vertical to the camera lens were included in the calculation of these ratios. The fruit data were derived from photos except for one direct measurement. Only fruit vertical to the camera lens were included in the calculation of these ratios. Fruits were green and unripe.

The fruit length to width ratios were 1.00:1 to 1.12:1 for the Hecho valley specimen (n=3) and 1.07:1 to 1.24:1 for the Aísa valley specimen (n=4).

4. Discussion and conclusion

The two Sorbus shrubs described above seem to belong to the same taxon. The Aísa example had larger leaves, perhaps due to more favourable conditions for growth. The two specimens look most like Sorbus mougeotii, based on the detailed taxon information in Rich et al. (2010)Rich, T.C.G., Houston, L., Robertson, A., & Proctor, M.C.F., 2010. Whitebeams, Rowans and Service Trees of Britain and Ireland. A monograph of British and Irish Sorbus L. B.S.B.I. Handbook No. 14. Botanical Society of the British Isles, London. and compared to the planted Sorbus mougeotii trees that I had found in the village of Elton, UK. Three key characters are the leaf lobe sinus depth, number of secondary veins arising from the mid-vein of a leaf (also known as lateral veins) and ratio of fruit length to fruit width. Table 2 compares the measures for these three characters from the Hecho and Aísa specimens, and taxon descriptions in Rich et al (2010)Rich, T.C.G., Houston, L., Robertson, A., & Proctor, M.C.F., 2010. Whitebeams, Rowans and Service Trees of Britain and Ireland. A monograph of British and Irish Sorbus L. B.S.B.I. Handbook No. 14. Botanical Society of the British Isles, London. and Flora Iberica (Aedo & Aldasoro, 1999Aedo, C. & Aldasoro, J.J., 1999. Sorbus in Castroviejo, S. (Coord.) Flora Iberica 6: 414-429. Real Jardín Botánico de Madrid-C.S.I.C. Madrid.).

In summary, the two shrubs seen in the Hecho and Aísa valleys in 2017Google Earth 7.3, 2017. Vertical aerial images of Hecho and Aísa valleys, Spanish Pyrenees, dated 2015. Published on the Internet at http://www.google.com/earth [accessed 30/07/2017]. appear to be Sorbus mougeotii. These records can be regarded as new ones for the Spanish Pyrenees in relation to Flora Iberica (Aedo & Aldasoro, 1999Aedo, C. & Aldasoro, J.J., 1999. Sorbus in Castroviejo, S. (Coord.) Flora Iberica 6: 414-429. Real Jardín Botánico de Madrid-C.S.I.C. Madrid.). Further recording would be very helpful in assessing whether this species occurs more widely in the Spanish Pyrenees.