I’ll start with a question. What do Lady’s Mantle, Great Burnet, Agrimony, Mountain Avens, Cotoneaster, cinquefolil (Potentilla), strawberries, raspberries, cherries, sloes, apples, rowans and almonds all have in common? The answer may come as a surprise to many; they are all members of the Rose family. This may shcok some of you, but I don’t have a great deal of time for the domesticate hybrid tea roses so common in many gardens.
Hybrid tea rose – looking nothing like the real roses
I think they’re vastly overrated and as many varieties do not produce pollen or nectar as far as insects are concerned they are a waste of space. My experience of working on members of the Rosaceae arose as a by-product of working on the bird cherry-oat aphid, the primary host of which is the bird cherry, Prunus padus (Leather & Dixon, 1981), and the bird cherry ermine moth, Ypomeuta evonymellus which specialises on the bird cherry (Leather & Lehti, 1982). Strangely, it was my interest in island biogeography, in particular the species-area relationship, that got me hooked on the Rosaceae. I had noticed while sampling bird cherry trees that relatively few insects attacked them, and so wondered if they were special in some way compared with other species of Prunus, and sure enough using host plant records, they did seem to be less insect friendly than their congeners (Leather, 1985). Having got hooked on counting dots on plant distribution maps and realising that the Rosaceae would be a great plant family to test the idea that the species-area relationship would be improved by confining it to a single family (Kennedy & Southwood, 1984), I embarked on a marathon dot counting and host plant record seeking quest (Leather, 1986).
For the paper, I restricted my analysis to the 59 species that Perrings & Walter (1962) listed as native or naturalised to the British Isles, but there are of course many more members of the Rosaceae than that to be found in Britain. They are an extremely important plant family both economically and horticulturally speaking, with over 2500 species in 90 genera to choose from (Sytsma, 2016). The Rose family is divided into four subfamilies based primarily on their fruit. The Amygdaloideae, those species characterised by the possession of fleshy stone fruits, almonds, cherries, peaches, plums etc. The Maloideae, trees with pomes, fruits in which the floral hypanthium becomes fleshy, e.g apples and pears. The Rosoideae, which includes species such as roses, and burnets, with dry fruits that do not open (achenes), and the brambles, raspberries and strawberries, which have drupelets, small, aggregated drupes, and finally the Spiraeoideae, species with dry fruits that open on one side (follicles) e.g Spirea, Physocarpus).
To me, however, the thing that makes a rose a rose, is the flower. Typically, rose flowers have five sepals which are easier to see before the flowers open and five petals, although there are always some exceptions; for example, Mountain
Sepals for the uninitiated; luckily I have a rose bush that seems to be able to flower all the year round (this picture taken October 28th)
Avens, Dryas octopetala, which as the name tells us, has eight petals but still manages to have that rose ‘look’.
Dryas octopetala an exception that proves the rule J By Jörg Hempel, CC BY-SA 3.0 de, https://commons.wikimedia.org/w/index.php?curid=28317727
As you might expect from a family that has produced the much loved (but not by me) hybrid tea roses, not all the flowers are white, even within the same species, brambles for example, range from the ‘normal’ white to rich
Pink hedgerow brambles, Sutton, Shropshire September 2020.
pinks, and many of the herbaceous members have bright yellow (e.g. Agrimony and Wood Avens) or orange (e.g Water Avens) flowers.
Delicate herbaceous plants with white and yellow flowers.
White flowers do, however, seem to be the rule in the woodier members of
Shrubby bushes with white flowers.
the family, although pink shading is not uncommon.
The ways in which the flowers are presented can also vary between species, single flowers being the exception rather than the rule.
Cloudbursts (corymbiform panicle), racemes and compound cymes, but still roses. Fun fact, Meadowseet, Filipendulal ulmaria, is rich in salicylic acid and can be used to cure headaches.
I hope you’ve enjoyed this ramble through the roses as much as me, but finally, as an entomologist, it would be remiss of me not to point you at one or two spectacular examples of insect-rose interactions.
Kennedy, C.E.J. & Southwood, T.R.E. (1984) The number of species of insects associated with British trees: a re-analysis. Journal of Animal Ecology, 53, 455-478.
Leather, S.R. (1985) Does the bird cherry have its ‘fair share’ of insect pests ? An appraisal of the species-area relationships of the phytophagous insects associated with British Prunus species. Ecological Entomology, 10, 43-56.
Leather, S.R. (1986) Insect species richness of the British Rosaceae: the importance of host range, plant architecture, age of establishment, taxonomic isolation and species-area relationships. Journal of Animal Ecology, 55, 841-860.
Leather, S.R. (1991) Feeding specialisation and host distribution of British and Finnish Prunus feeding macrolepidoptera. Oikos, 60, 40-48.
Leather, S.R. & Dixon, A.F.G. (1981) Growth, survival and reproduction of the bird-cherry aphid, Rhopalosiphum padi, on it’s primary host. Annals of Applied Biology, 99, 115-118.
Leather, S.R. & Lehti, J.P. (1982) Abundance and distribution of Yponomeuta evonymellus (Lepidoptera,Yponomeutidae) in Finland. Notulae Entomologicae, 62, 93-96.
Perring, F.J. & Walters, S.M. (1962) Atlas of the British Flora. BSBI Nelson, London & Edinburgh.
Sytsma, K.J. (2016) Rosaceae, Encyclopaedia Britannica.