Caragana

This pea shrub is from Turkestan in Central Asia. It is very similar to its eastern relative, the Siberian pea tree (C. arborescens), which is very commonly planted in Finland, for example as hedging. The Turkish species has slightly darker leaves and is more shrub-like than the Siberian. It flowers in spring with the typical yellow pea-like flowers, and the seed-pods which form later are again typical of the pea family.

In Finland the Turkish pea shrub has not been much tried, though from experience at Mustila it seems very hardy. It is not as susceptible to mildew as the Siberian species, so could well be used as a replacement. It thrives in poor soils spots because its roots can fix nitrogen from the atmosphere, like the other plants of the pea family.

The Russian pea shrub flowers in June, when it is covered in the typical flowers of the pea family, yellow and butterfly-shaped. The bright green leaves have four lobes which are broadest near the tip, blunt but pointed at the end of the central vein.

This is a beautiful hardy shrub. It is healthy and demands no special care, nor does it produce root suckers. It thrives in sunshine and on sandy soil, thanks to its ability, characteristic of the pea family, to fix atmospheric nitrogen with root bacteria. It can also be used as hedging.

At Mustila the Russian pea shrub grows on Etelärinne (Southern Slope), though due to excess shade it is not at its best there, either in foliage or in flower.

The Siberian pea tree was brought to Finland in the 1740s. Pietari Kalm brought seed from St. Petersburg, thinking he was introducing a new edible plant, but the slightly poisonous pods make this species unsuitable. However, in recent times it has been widely used in gardens, parks, and at railway stations. It grows quite large and erect, with small leaves, and is at its best when it flowers in June with small yellow flowers typical of the pea family.

Growing native in Siberia and north-eastern China, this species is the most commonly used in Finland in garden hedges, ranking with the hawthorn Crataegus grayana. Its branches are softer and easier to trim than those of the hard and thorny hawthorn and the clippings make excellent compost. Its use has decreased, however, because of the tendency to mildew on cut hedges, which turns the leaves grey. The hardy Siberian pea tree is suitable for open sunny dry areas, where it grows into a large beautifully flowering shrub, much better looking than as a cut hedge.