Malus Mill.

Li, Jing-chao, Liu, Jian-quan & Gao, Xin-fen, 2022, A revision of the genus Malus Mill. (Rosaceae), European Journal of Taxonomy 853, pp. 1-127 : 12-15

Genus Malus Mill.

Gardeners Dictionary Abridged, 4 th Ed., Vol. 2: Malus ( Miller 1754) .

Pyrus sect. Malus Tourn. , Institutiones Rei Herbariae Vol. 3: tab. 406 ( Tournefort 1700). – Pyrus sect. Malus Tourn. ex DC. , Prodromus Systematis Naturalis Regni Vegetabilis Vol. 2: 635 ( de Candolle 1825). – Pyrus subgen. Malus (Tourn.) Focke , Die natürlichen Pflanzenfamilien 3 rd Ed., 3 (3): 24 ( Focke 1888).

Type species

Malus sylvestris (L.) Mill.

Description

Trees or shrubs, deciduous or semi-evergreen. Branches terete, generally unarmed. Leaves unifoliate, alternate, petiolate, stipular. Lamina oval to ovate, margin crenate to serrulate, serrate or lobed. Inflorescence umbellate or corymbose. Flowers usually 3‒6, pedicellate. Stamens 15‒50, with yellow anthers and white filaments. Hypanthium bowl-shaped, glabrous or pubescent. Petals 5, suborbicular to obovate, white to red, with 5 sepals persistent or caducous. Styles 3‒5, connate at base, glabrous or pubescent. Ovary inferior, 3‒5-locular, with 2 ovules in each locule. Pome stone cells present in a few species. Seeds semicircular or spindly, black or brown, 1 or 2 in each locule.

Chromosome number

x = 17, usually diploid, triploid, tetraploid, and polyploid.

Distribution

Widely distributed in North temperate zone.

Key to species

1. Microphyll (225‒2025 mm 2) most common ..................................................................................... 2

– Notophyll (2025‒4500 mm 2) most common .................................................................................. 20

2. Insertion points of lamina base on either side of petiole are symmetrical ........................................ 3

– Insertion points of lamina base on either side of petiole are asymmetrical .................................... 17

3. Leaf margin generally unlobed, or lobed in young leaves ................................................................ 4

– Leaf margin distinctly lobed, or divided ......................................................................................... 13

4. Lamina base cuneate or rounded ...................................................................................................... 5

– Lamina base rounded, truncate, wide-cuneate or cordate ................................................................. 9

5. Lamina elliptic to ovate, elliptic ovate or triangular ovate ............................................................... 6

– Lamina obovate, oblong to oval or rotund ........................................................................................ 7

6. Tree; leaf apex retuse to caudate; abaxial blade puberulous or glabrescent; umbel ........................... .................................................................................................................... 1. M. baccata (L.) Borkh. – Small tree or shrub; leaf apex acute, rounded or obtuse; blade glabrous or villous on midvein, sometimes lobed; corymb ........................................................... 20. M. angustifolia (Aiton) Michx.

7. Young leaves piliferous, then glabrescent; small pome, with maximum diameter no more than 4.5 cm ............................................................................................................................................... 8

– Abaxial blade puberulous in adult leaves; sepals caducous; styles 3 or 4, with dense tomentum at base; pome ca 3.0‒8.0 cm in diameter, subglobose or coniform, yellow or green ............................. ...................................................................................................... 4. M. kirghisorum Al.Fed. & Fed.

8. Small tree or shrub; hypanthium densely lanuginous; sepals densely puberulous, persistent; styles 5, rarely 4, basally densely puberulent; pome solitary, ca 2.5‒4.5 cm in diameter ................................ ........................................................................................................ 3. M. sieversii (Ledeb.) M.Roem.

– Tree; hypanthium glabrous; sepals abaxially puberulous or glabrous, adaxially densely puberulous, caducous; styles 3‒5, glabrous; pome ca 1.0‒ 1.3 cm in diameter ...................................................... ..................................................................................... 11. M. xiaojinensis M.H.Cheng & N.G.Jiang

9. Lamina ovate, broadly ovate to elliptic ovate or rotund ................................................................. 10

– Lamina ovate to oblong or triangular ovate .................................................................................... 12

10. Leaf margin occasionally lobed, apex acuminate or acute; hypanthium densely lanuginous; styles 5, basally puberulous .......................................................... 14. M. tschonoskii (Maxim.) C.K.Schneid.

– Leaf margin unlobed, apex usually acuminate; hypanthium puberulous or glabrous; styles 5, basally glabrous ............................................................................................................................................11

11. Small tree or shrub; lamina glabrous; umbel; pome solitary, ca 2.0‒ 3.5 cm in diameter, subglobose, yellow .......................................................................................................... 7. M. sylvestris (L.) Mill.

– Tree; lamina puberulous or glabrous; corymb; pome ca 1.0‒ 1.5 cm in diameter, ellipsoidal, yellow to red, with fruit spots .............................................................. 17. M. prattii (Hemsl.) C.K.Schneid.

12. Small tree or shrub; lamina puberulous, sometimes 3-lobed, rarely 5-lobed; umbel; hypanthium puberulous or glabrous; sepals caducous; styles 3‒5, basally densely puberulent; pome ca 0.6‒0.8 cm in diameter, subglobose or oblate, yellow or red ......... 8. M. toringo (Siebold) Siebold ex de Vriese

– Small tree; lamina glabrous or puberulous, sometimes lobed; corymb; hypanthium densely puberulous; sepal persistent; styles 5, pubescent at base; pome ca 2.0‒3.0 cm in diameter, subglobose, yellow.......................................................... 21. M. ioensis (Alph.Wood) Britton

13. Lamina palmately lobed or divided ................................................................................................ 14

– Lamina pinnately lobed or divided ................................................................................................. 15

14. Tree; lamina base rounded or cuneate, apex acute, pubescent on abaxial blade, lobed; sepals persistent; styles 5, pubescent at base; pome ca 1.0 cm in diameter, oval or obovate ......................................... ......................................................................................... 23. M. florentina (Zuccagni) C.K.Schneid.

– Small tree or shrub; lamina base cordate or cuneate, apex acute or acuminate, puberulous, 3-lobed; sepals caducous or persistent; styles 4 or 5, glabrous; pome ca 0.8‒1.0 cm in diameter, subglobose, yellow to red ................................................................................... 26. M. komarovii (Sarg.) Rehder

15. Lamina base usually wide-cuneate, sometimes rounded or cordate; umbelliform corymb (appearance resembles umbel) ............................................................................................................................ 16

– Lamina base usually rounded or cordate, sometimes cuneate; corymb; sepals abaxially glabrous or puberulous, adaxially densely puberulous, persistent; styles 5, pubescent at base; pome ca 2.5‒3.5 cm in diameter, subglobose, yellow ............................................................... 22. M. coronaria (L.) Mill.

16. Lamina elliptic to ovate, piliferous, pubescent on midvein, usually 3-lobed or divided, sometimes unlobed; pome ca 1.0‒ 1.3 cm in diameter, ellipsoidal to subglobose, yellow ................................... ................................................................................................... 10. M. toringoides (Rehder) Hughes

– Lamina oval to ovate, puberulous when young, then abaxially glabrescent, usually 3‒5-divided; pome ca 0.6‒0.8 cm in diameter, subglobose, yellow to red ...... 12. M. transitoria (Batalin) C.K.Schneid.

17. Indumentum on young leaves, then glabrescent ............................................................................. 18

– Indumentum on abaxial blade or midvein, sometimes glabrous .................................................... 19

18. Lamina oval to ovate, usually aubergine in young leaves, base cuneate, rarely rounded, apex acuminate, rarely retuse, discolorous; umbel; styles 3, rarely 4, basally puberulent; pome ca 0.8‒0.9 cm in diameter, subglobose, yellow to red ............................................. 2. M. hupehensis (Pamp.) Rehder

– Lamina elliptical to oval, base cuneate or cordate, oblique, apex acuminate or acute, rarely obtuse, sporadically 3-lobed; umbelliform corymb; styles 2‒5 (3‒4), glabrous; pome ca 1.5‒2.0 cm in diameter, coniform, yellow to red .................................................... 6. M. fusca (Raf.) C.K.Schneid.

19. Lamina oblong to orbicular, base cuneate; styles 5, glabrous or with dense tomentum at base, stigma clavate; pome ca 2.0‒3.0 cm in diameter, subglobose or coniform, yellow or red ............................ .......................................................................................................... 5. M. orientalis Uglitzk. ex Juz.

– Lamina elliptic to ovate, base rounded, cordate or cuneate; styles 4 or 5, basally crinite; pome ca 1.0‒ 1.5 cm in diameter, subglobose, tapering, red .......................................... 9. M. rockii Rehder

20. Insertion points of lamina base on either side of petiole are symmetrical ...................................... 21

– Insertion points of lamina base on either side of petiole are asymmetrical; lamina oblong to ovate, base rounded or cuneate, apex acute or acuminate, pubescent when young then glabrescent, or glabrous; styles 5, pubescent at base; pome ca 2.5‒5.5 cm in diameter, subglobose, yellow to red .................. ........................................................................................................... 25. M. doumeri (Bois) A.Chev.

21. Leaf margin generally unlobed, sometimes lobed or divided ......................................................... 22

– Leaf margin distinctly lobed, or divided, occasionally unlobed ..................................................... 23

22. Small tree; lamina oval to ovate, base rounded, pubescent on midvein and abaxial blade; styles 4, glabrous; pome ca 1.5‒2.0 cm in diameter, subglobose or pyriform, yellow to red ........................... ........................................................................ 13. M. sikkimensis (Wenz.) Koehne ex C.K.Schneid.

– Tree; lamina oval to oblong, base cordate, rounded or truncate, villous on abaxial blade, rarely 3‒5-lobed; styles 3‒5, glabrous; pome ca 1.5‒2.0 cm in diameter, subglobose, red or yellow, with fruit spots ........................................................................................ 19. M. ombrophila Hand. -Mazz.

23. Lamina palmately lobed or divided, ovate, base cordate, pubescent on abaxial blade; umbel; styles 5, pubescent at base; pome ca 1.0‒2.0 cm in diameter, subglobose or ellipsoidal, red ...................... .................................................................................. 24. M. trilobata (Labill. ex Poir.) C.K.Schneid.

– Lamina pinnately lobed or divided ................................................................................................. 24

24. Sepals persistent .............................................................................................................................. 25

– Sepals caducous, abaxially glabrous, adaxially puberulous; lamina oval to ovate, base rounded, truncate or cordate, puberulous or glabrous, usually 3-lobed; styles 3, rarely 2 or 4, glabrous or puberulous; pome ca 1.0‒ 1.5 cm in diameter, ellipsoidal, yellow to red, with fruit spots ................. .......................................................................................... 16. M. kansuensis (Batalin) C.K.Schneid.

25. Small tree or shrub; lamina usually oval, sometimes elliptical, base rounded, truncate or cordate, apex acute or obtuse, with dense pubescence on midvein, usually 3‒6-lobed; styles 3 or 4, glabrous; pome ca 0.8 cm in diameter, subglobose, yellow to red, with white fruit spots ................................. .................................................................................................................. 15. M. honanensis Rehder

– Tree; lamina oval to oblong, base cordate, rounded or truncate, apex acuminate, acute or obtuse, pubescent on abaxial blade, usually 3‒5-lobed; styles 5, glabrous; pome ca 1.0‒ 1.5 cm in diameter, subglobose, oblate or oval, red, with white fruit spots ....................................................................... ....................................................................................... 18. M. yunnanensis (Franch.) C.K.Schneid.