Hornschuchia Nees

Vilela, Lucas & Lopes, Jenifer De Carvalho, 2022, Hornschuchia (Annonaceae), an endemic and threatened genus from the Brazilian Atlantic Forest, European Journal of Taxonomy 828, pp. 75-108 : 77-78

Genus Hornschuchia Nees

Flora 4 (1): 302 ( Nees 1821). − Type species: Hornschuchia bryotrophe Nees.

Mosenodendron R.E.Fr., Kongliga Svenska Vetenskaps Akademiens Handlingar , ser. 3 34 (5): 8 ( Fries 1900). – Type species: Mosenodendron insigne R.E.Fr.

Description

Trees to shrubs. Leaves chartaceous to coriaceous with primary vein impressed adaxially. Inflorescence 1-flowered or 2–22-flowered; axillary, supra-axillary, terminal or cauliflorous, i.e., ramiflory, trunciflory, flagelliflory. Flowers white, rarely pinkish, trimerous; three sepals and six petals in two whorls; calyx with sepals completely connate, rarely connate at the base; corolla with linear petals; stamens 3–18; carpels 2–9. Fruit with 1–5 monocarps, monocarps obovate, globose, ellipsoid, obloid, fusiform; stipe 1.5–9 mm long, subsessile to sessile. Seed 1–8, globose, obovoid, obloid-ellipsoid, ellipsoid, flattened-ellipsoid, with aril, rarely without aril.

Hornschuchia is recognized by its small and white flowers, with linear petals and cupuliform calyx. It is similar to Trigynaea and Bocagea ; however, the petals in these two genera are ovate, elliptic or lanceolate ( Johnson & Murray 1995).

Key to the species of Hornschuchia Nees

1. Leaves with commissural veins evident ............................................................. H. bryotrophe Nees

− Leaves without commissural veins ................................................................................................... 2

2. Inflorescence axillary, supra-axillary to terminal or ramiflorous ...................................................... 3

− Cauliflorous, except ramiflorous ......................................................................................................11

3. Inflorescence 1-flowered ................................................................................................................... 4

− Inflorescence 2–22-flowered ........................................................................................................... 10

4. Calyx connate at the base with triangular apex ....................................... H. citriodora D.M.Johnson

− Calyx completely connate (cupuliform) with truncate apex ............................................................. 5

5. Calyx 3–8 mm long .......................................................................................................................... 6

− Calyx 1–2(–3) mm long .................................................................................................................... 8

6. Stamens 10, 4 mm long, carpels 5.5 mm long. Monocarp obloid with acute apex, 20–24 × 9–12 mm, stipe 1–2 mm long .................................................................... H. mellosilvae L.Vilela & J.C.Lopes

− Stamens 3–6, 2–3 mm long, carpels 2–3 mm long. Monocarp globose to ellipsoid with rounded apex, 8–13 × 5–9 mm, sessile .................................................................................................................... 7

7. Floral bud cylindrical with obtuse apex. Fruit 1 monocarp with persistent calyx .............................. .................................................................................................................. H. lianarum D.M.Johnson

− Floral bud globose to ovoid to conical with acute apex. Fruit 2–5 monocarps with caducous calyx ... .................................................................................... H. mediterranea Mello-Silva & D.M.Johnson

8. Calyx glabrescent. Monocarp sessile ................................................................... H. polyantha Maas

− Calyx densely covered in trichomes. Monocarp stipe 1.5–3 mm long ............................................. 9

9. Leaves narrowly elliptic to elliptic, oblanceolate to narrowly oblong, obovate or rarely lanceolate. Pedicel 7–37 mm long ............................................................................................ H. myrtillus Nees

− Leaves narrowly ovate to ovate or lanceolate. Pedicel 1–7 mm long ..... H. alba (A.St.-Hil.) R.E.Fr.

10. Floral bud cylindrical. Monocarp fusiform, 5–8 mm wide, densely covered in trichomes, whitish in vivo ........................................................................................................... H. obliqua Maas & Setten

− Floral bud conical. Monocarp globose, 16–19 mm wide, glabrous, green in vivo ............................ ..................................................................................................................... H. santosii D.M.Johnson

11. Trunciflory ...................................................................................................................................... 12

− Flagelliflory, i.e., inflorescence branches 4.5–100 cm long, emerging from the basal part of the trunk and running near the soil ................................................................................................................. 13

12. Inflorescence branches 6–19 cm long ...................................................... H. leptandra D.M.Johnson

− Inflorescence emerging close to the trunk ............................................. H. cauliflora Maas & Setten

13. Calyx glabrescent. Bracts caducous .................................................................... H. polyantha Maas

− Calyx densely covered in trichomes. Bracts persistent .......................................... H. myrtillus Nees