A new species of Boehmeria (Urticaceae), B. burgeriana Wilmot-Dear, Friis & Kravtsova, endemic to Costa Rica

Summary. A new species of Boehmeria with 'multiple' (double and triple) flowers and fruits, Boehmeria burgeriana, is described from Costa Rica. The derivation of its unusual flowers and fruits is discussed. Fruit anatomy provides supporting evidence for its inclusion within this genus. Boehmeria burgeriana Wilmot-Dear, Friis & Kravtsova sp. nov. ab omnibus ceteris speciebus generis tepalis florum masculorum appendicem subapicalem longissimam 1 - 2 mm longam longitudinem tepali aequantem vel excedentem ferentibus et floribus femineis paribus vel ternis lateraliter connatis fructum latissimum bilocularem vel trilocularem formantibus differt. B. cylindricae foliis atque stigmate aliquantum similis sed habitu sub-prostrata, inflorescentiis axillaribus nec pseudospiciformibus et mesocarpio fructus multilamellato etiam differt. Typus: Costa Rica, San Jose province, Upper Rio Hondura, along Rio Clara, steep wet slopes below La Palma, 1 Jan. 1967, Burger 4137 (F, holotypus & isotypus; MO, NY, isotypi). 'Species of uncertain position', Burger (1975: 271 - 272; 1977: 282); "species of uncertain identity", Wilmot-Dear & Friis (1996). Perennial herb or subshrub up to 0.5 m, erect or more often at least partly prostrate and rooting at the nodes; ultimate branches slender or fairly robust, 0.6 1.5 mm diameter with abundant short or long (0.1 - 1.5 mm), soft, spreading, yellowish-white hairs, but soon glabrescent and dark red. Leaves opposite, rather variable even on one plant, usually some isomorphic, others dimorphic in size and especially in petiole length, with lamina of larger leaf up to 1.5 times as long as smaller and petiole up to three times as long; lamina ovate, very slightly asymmetrical, 1.7 - 11 x 1 - 7 cm, often relatively broad, 11/2 - 2(- 2 1/2) times as long as wide, margin coarsely serrate or crenate nearly to base, with teeth increasing in size but only slightly in number as leaf size increases, number of teeth on wide side c. 10 on smallest leaves and only c. 20 on largest leaves; apex acuminate, consisting of single long tooth which is broadly acute or ? rounded at extreme tip, base asymmetrical and rather variable, narrowly cuneate to rounded or ? truncate; basal pair of lateral veins extending a little into upper half of lamina