Question

Which plant is described by these clues? Its genus name honours a father-and-son pair of royal gardeners in Paris, the elder of whom raised the first of these trees in Europe from seed shipped across the Atlantic in 1601. Each flower is two-sided rather than radial: one broad {petal} standing erect behind two flaring side petals, and two more fused into a boat that hides nine {stamens} joined in a sheath with a tenth left free. Its species epithet marks it a counterfeit, naming it the false version of a thorny, feather-leaved warm-country genus that early botanists took it for. Its roots are beaded with small {nodules} housing bacteria that pull nitrogen straight out of the air, which lets it seize raw, nutrient-poor ground where other trees stall. On vigorous shoots a pair of short, stiff spines sits one on either side of every leaf base, hardened out of the leaf {stipules} themselves rather than sprouting from the twig. Its natural home is the Appalachian and Ozark uplands of eastern North America, on rocky slopes, open woodland and disturbed ground. The leaves are divided once only, into 7 to 19 oval {leaflets} each 1 to 2 inches (2.5 to 5 cm) long, with a single odd one closing the tip. In late spring white flowers hang in drooping tassels 4 to 8 inches (10 to 20 cm) long, heavily and sweetly scented, giving way to flat brown pods 2 to 4 inches (5 to 10 cm) long. On an old trunk the bark is dark brown to almost black and cut into deep furrows between hard, interlacing, rope-like ridges. Its cut timber is exceptionally hard and slow to decay, yet the standing wood is brittle for the speed it grows, so mature specimens shed limbs in ice storms and high wind. Its inner bark, seeds and leaves carry toxalbumins chemically akin to ricin, and horses that chew the bark or the young shoots sicken within an hour or two. Split posts of its timber are famous for standing in fences for decades without rotting, and across central Europe its nectar yields the pale, slow-crystallising honey still sold under the name of the unrelated tree it was long mistaken for.

Accepted Answer

Robinia pseudoacacia 'Frisia'

Name That Plant #043