ROSACEAE

LXXX. ROSACEAE View in CoL 1

Trees, shrubs or herbs. Leaves usually alternate and stipulate. Flowers regular, usually hermaphrodite, perigynous or epigynous. Hypanthium flat, concave or tubular. Sepals usually 5, sometimes with epicalyx. Petals usually 5, free, sometimes absent. Stamens usually 2, 3 or 4 times as many as the sepals, sometimes 1-5 or indefinite. Carpels 1 to numerous, free or connate, sometimes adnate to the hypanthium. Ovules usually 2, sometimes 1 or more, anatropous. Styles free, rarely united. Fruit of one or more achenes, drupes or follicles, or a pome, the hypanthium sometimes becoming coloured and fleshy. Endosperm usually absent.

It is convenient, in this family, to use the term ‘hypanthium’ to denote that part of the flower which bears the sepals, petals and stamens on its outer or upper margins, and on which the carpels are borne. The hypanthium is often, at least in part, receptacular in nature, but it is sometimes fused, to a variable extent, with the walls of the carpels, the exact line of demarcation being difficult to determine.

The family is notable for the large number of genera which are cultivated either for ornament or for food. Apomixis, either facultative or obligate, is a feature of the reproduction of several genera of the two largest European subfamilies, the Rosoideae and Maloideae ; and in some of these, notably Rubus , Alchemilla and Sorbus , the number of taxa described at the level of species is very large. This situation has been met by describing and keying a number of species which represent the whole range of variation. The remaining species (at least those described in Standard Floras or important monographs) are then listed after the species which they most closely resemble, together with a note of the territories in which they occur.

1 Trees,shrubsordwarfshrubs

2 Petalsc.8; procumbentdwarf shrub 16. Dryas 2 Petals0, 4 or5

3 Leaves pinnate or digitate

4 Flowers in dense capitula; petals 0

5 Stamens 2; fruit dry 15. Acaena 5 Stamens numerous; fruit fleshy 14. Sarcopoterium 4 Flowers not in dense capitula; petals 4 or 5

6 Carpels and fruit exposed on the hypanthium

7 Prickly; fruit a head of drupelets 9. Rubus

7 Unarmed; fruit a head of achenes or follicles

8 Carpels 5, developing into follicles 1. Sorbaria

8 Carpels more than 5, developing into achenes

19. Potentina 6 Carpels enclosed in the hypanthium

9 Usually spiny shrubs; carpels numerous, free 10. Rosa

9 Unarmed trees; carpels 2-5, adnate to the hypanthium

28. Sorbus 3 Leaves simple

10 Leaves opposite; sepals and petals 4 7. Rhodotypos 10 Leaves alternate; sepals and petals 5

11 Carpels not adnate to the hypanthium; fruit not a pome

12 Flowers yellow 8. Kerria

12 Flowers white, pink, red or purple

13 Leaveslobed

14 Fruit of 1 or more drupelets 9. Rubus

14 Fruit of several follicles

15 Stipules absent; carpels free 3. Spiraea

15 Stipules caducous; carpels connate at base

2. Physocarpus

13 Leaves not lobed

16 Carpel 1; fruit a drupe 35. Prunus

16 Carpels more than 1; fruit of several follicles

17 Carpels free 3. Spiraea

17 Carpels connate at base 4. Sibiraea 11 Carpels enclosed in and adnate to the hypanthium; fruit a pome

18 Flowers solitary

19 Flowers less than 1 cm in diameter; fruit red or black

31. Cotoneaster

19 Flowers more than 1 cm in diameter; fruit brown,

green or yellow

20 Sepals shorter than petals, dentate 25. Cydonia

20 Sepals longer than petals, entire 33. Mespilus

18 Flowers in 2- to many-flowered inflorescences

21 Walls of carpels becoming stony in fruit

22 Leaves entire 31. Cotoneaster

22 Leaves crenate-dentate or serrate or lobed

23 Evergreen; stipules caducous 32. Pyracantha

23 Deciduous; stipules persistent 34. Crataegus

21 Walls of carpels becoming cartilaginous in fruit

24 Flowers in compound corymbs or panicles

25 Evergreen; flowers in panicles 29. Eriobotrya

25 Deciduous; flowers in compound corymbs 28. Sorbus

24 Flowers in umbels, racemes or few-flowered clusters

26 Petals linear to oblong-ovate, not clawed

30. Amelanchier

26 Petals obovate or orbicular, clawed

27 Styles free; flesh of fruit with stone-cells 26. Pyrus

27 Styles connate at base; flesh of fruit with few or no stone-cells 27. Malus 1 Herbs 28 Petals 0 29 Leavessimpleordigitately divided 30 Annual; stamens 1(—2) 24. Aphanes 30 Perennial; stamens 4-10 31 Carpels 5-12 20. Sibbaldia 31 Carpel 1 23. Alchemilla 29 Leaves pinnate 32 Stamens 2; hypanthium with 4 spines 15. Acaena 32 Stamens 4 or numerous; hypanthium without spines

13. Sanguisorba 28 Petals 4 or more 33 Petalsc.8 16. Dryas 33 Petals4,5 or6 34 Sepals 4-6; epicalyx absent 35 Flowers yellow; fruit with hooked bristles 11. Agrimonia 35 Flowers white, cream, purple or red; fruit without bristles

36 Stipules absent; carpels 3 5. Aruncus

36 Stipules present; carpels 6 or more

37 Leaves pinnate, with small leaflets between the larger ones; fruit a head of achenes 6. Filipendula

37 Leaves undivided, digitate, or pinnate with equal leaflets; fruit a head of drupelets 9. Rubus 34 Sepals 4-5; epicalyx-segments 4-5 38 Carpels and achenes enclosed in the hypanthium

12. Aremonia 38 Carpels and achenes exposed

39 Leaves pinnate or lyrate

40 Styles long, persistent 17. Geum

40 Styles short, deciduous 19. Potentina

39 Leaves ternate, digitate or digitately lobed

41 Receptacle swollen, and fleshy or spongy in fruit 42 Petals purple 19. Potentina 42 Petals yellow or white

43 Epicalyx-segments 3-toothed at apex; petals yellow

22. Duchesnea 43 Epicalyx-segments not toothed at apex; petals white

21. Fragaria 41 Receptacle not swollen in fruit

44 Petals 1-2 mm; stamens 5(—10) 20. Sibbaldia 44 Petals more than 2 mm; stamens 10 or more

45 Carpels more than 6 19. Potentina 45 Carpels 2-6

46 Flowers 4-merous 19. Potentina 46 Flowers 5-merous 18. Waldsteinia

Subfam. Spiraeoideae

Stipules sometimes absent. Flowers 5-merous. Hypanthium flat, concave or campanulate, without carpophore; epicalyx absent; stamens 15 to numerous; carpels 1-5, whorled, free or connate at base, not sunk in hypanthium. Fruit of 1-5 follicles; seeds 2 or more. Basic chromosome number 8 or 9.