Scarlet Runner bean Phaseolus coccineus

Growing vegetables in the flower border has become fashionable in recent years but here's a vegetable that always been easy to appreciate for its decorative value - the runner bean. What other climber has such vivid flowers and also makes a nutritious addition to Sunday dinner? Scarlet runner bean hails from the mountainous regions of Guatamala, Mexico and Panama so it's travelled a long way on its journey to the gardens and allotments of Britain .... and changed a good deal along the way. The seeds and pods are monstrous compared with the diminutive wild versions and the pods have been bred to reduce the stringy tissue and parchment layer in the pod wall that would make wild pods shatter and release seeds as they dry out. Runner beans are usually grown as annuals (I've just sown what I hope will be an early crop) but they are perennials in the wild and if you can keep the roots frost-free through the winter they'll produce a second year's growth, albeit with inferior pod production. If you are of a curious nature and fancy some amateur plant breeding you could try crossing French beans with runner beans, by carefully removing stamens from French bean flowers with fine tweezers before they shed pollen and then pollinating the flowers with runner bean pollen a day or two later. The cross works with French beans as the female parent, but not the other way about.

Jade Vine Strongylodon macrobotrys

I first encountered this sensational plant at the Chelsea Flower Show in 1973, when I was a student, and didn't see it again until I visited its native country - the Philippines - in the late 1980s. I don't think I've seen another plant with a flower colour that can match it. It's now an endangered species, disappearing along with its tropical rainforest habitat. The plant is a climber and the flowers are pollinated by bats. The large racemes of flowers are pollinated by bats and dangle from long racemes from below the tree canopy - a habit known botanically as flagelliflory, that provides an uninterrupted flight path for bat pollinators.

 Fortunately we now have a plant flourishing in the Botanic Garden tropical house at Durham University. This is the first raceme of flowers to come into bloom this year and there are about another twenty or so still in bud, so it will be putting on a fine display over the coming weeks. 

Jade vine's flowers are typical of the pea family, with a standard petal and two wing petals on either side of a keel petal that's shaped like a claw. Inside the keel lie the stamens and the stigma at the tip of a long style. When a bat probes for nectar in the throat of the flower it pushes downwards on the keel petal and the stigma protrudes, forcing out a plug of pollen onto the bat's fur. It's a pity we don't have any suitable resident bats in our glashouse.

There's also a fine specimen growing in the glasshouses at Roundhay Park near Leeds and another at Cambridge University Botanic Garden.

Sturt's Desert Pea: Clianthus formosus

I've only ever grown this wonderful plant once, raising it from seed and coaxing it to produce this single cluster of fabulous flowers before making the mistake of giving it too much water. It's not called a desert pea for nothing - wet roots and humid conditions are death to it. Trouble is, if you keep it hot and dry (as I did with the two other seedlings I raised) it succumbs to attacks of red spider mite very easily in greenhouses in England. So, when it comes to watering it, you're damned if you do and you're damned if you don't. The only solution is to move to South Australia, where it's the state flower and is perfectly at home. I gather that this plant also now goes under the name of Swainsona formosa.