Croton, Linnaeus, 1753

Pereira, Amanda Da Paixão Noronha, Riina, Ricarda & Caruzo, Maria Beatriz Rossi, 2022, Croton (Euphorbiaceae) of the Brazilian state of Paraná: an annotated checklist, species distribution, and identification key, Phytotaxa 570 (3), pp. 231-274 : 233-235

Key to the species of Croton from Paraná state

1. Prostrate subshrubs. Young branches and leaves with whitish to blackish stellate trichomes. Leaves suborbiculate to reniform ..... ................................................................................................................................................................................ C. glechomifolius

- Trees, shrubs or erect subshrubs. Young branches without blackish stellate trichomes. Leaves never suborbiculate or reniform ..... ........................................................................................................................................................................................................... 2

2. Leaves with acropetiolar or basilaminar nectary glands (rarely absent in some leaves of C. ichthygaster ) .................................... 3

- Leaves without acropetiolar or basilaminar nectary glands ........................................................................................................... 21

3. Young branches angular, costate; with lepidote subentire trichomes. Pistillate flowers urceolate ................................. C. salutaris

- Young branches cylindrical to slightly flattened, never costate; with stellate, stellate-porrect, stellate-lepidote, rosulate or dendritic trichomes. Pistillate flowers rotate, campanulate or subcampanulate .............................................................................................. 4

4. Young branches with a dense, hirsute indumentum of stellate-porrect trichomes. Inflorescences densely congested. ...................... ......................................................................................................................................................................................... C. aberrans

- Young branches pilose, sparsely to densely pubescent with stellate, stellate-lepidote, rosulate or dendritic trichomes. Inflorescences lax or congested ................................................................................................................................................................................ 5

5. Stipitate acropetiolar nectary glands, facing up (adaxial side). Leaves with stellate-lepidote trichomes .............. C. macrobothrys

- Stipitate acropetiolar, facing down (abaxial side), sessile acropetiolar or basilaminar nectary glands. Leaves with stellate, rosulate or dendritic trichomes ....................................................................................................................................................................... 6

6. Stamens 80–130. Styles basally connate, forming a column at the top of the ovary ................................................. C. vulnerarius

- Stamens up to 60. Styles free, not forming a column at the top of the ovary .................................................................................. 7

7. Adaxial leaf surface glabrescent. Pistillate and staminate flowers reduplicate-valvate. Fruits strongly muricate ........... C. eichleri

- Adaxial leaf surface glabrescent to pubescent. Pistillate and staminate flowers valvate. Fruits smooth or inconspicuously verrucose ........................................................................................................................................................................................... 8

8. Inflorescences with a sterile zone between pistillate and staminate flowers ............................................................... C. lundianus

- Inflorescences without a sterile zone between pistillate and staminate flowers .............................................................................. 9

9. Nectary glands stipitate to shortly stipitate, acropetiolar. Stamens ca. 60. Fruits inconspicuously verrucose ........... C. celtidifolius

- Nectary glands, sessile, basilaminar, sometimes absent in a few leaves of the same plant. Stamens up to 20. Fruits smooth ...... 10

10. Leaf apex slightly emarginate to emarginate, sometimes mucronate. Nectary glands absent in some leaves .......... C. ichthygaster

- Leaf apex neither emarginate nor mucronate. Nectary glands present in all leaves ...................................................................... 11

11. Adaxial leaf surface glabrous .................................................................................................................................. C. polygonoides

- Adaxial leaf surface with trichomes ............................................................................................................................................... 12

12. Xylopodium present. Leaves with patelliform nectary glands along the margin ................................................. C. antisyphiliticus

- Xylopodium absent. Leaves without patelliform nectary glands along the margin ....................................................................... 13

13. Subshrubs. Leaf margin irregularly dentate ................................................................................................................................... 14

- Shrubs to trees. Leaf margin entire to slightly serrate..................................................................................................................... 15

14. Bracts with glands. Pistillate flowers sessile; sepals unequal; styles pubescent ....................................................... C. glandulosus

- Bracts without glands. Pistillate flowers pedicellate, sometimes pedicels recurved; sepals equal; styles glabrous ....... C. trinitatis

15. Acropetiolar nectary glands only visible from below. Inflorescences with bisexual lower cymules. Pistillate flowers pedicellate. Columella apex inconspicuous and unlobed ............................................................................................................... C. urucurana

- Acropetiolar nectary glands only visible from above. Inflorescences with unisexual lower cymules. Pistillate flowers sessile to subsessile. Columella apex with three inflated lobes ..................................................................................................................... 16

16. Inflorescences congested ...................................................................................................................................................... C. reitzii

- Inflorescences lax ........................................................................................................................................................................... 17

17. Styles tetrafid (12 terminal tips). Fruits with stellate-rosulate trichomes .................................................................. C. thermarum

- Styles bifid (6 terminal tips). Fruits with stellate (no rosulate) trichomes ..................................................................................... 18

18. Young branches smooth. Styles densely pubescent (at least half of its length) ................................................................ C. lanatus

- Young branches striate. Styles sparsely pubescent (just at the base) or glabrous .......................................................................... 19

19. Inflorescences axis cylindrical. Staminate flowers sessile to subsessile .............................................................. C. sanctae-crucis

- Inflorescences axis flattened. Staminate flowers pedicellate ......................................................................................................... 20

20. Young branches glabrescent. Leaves membranous, ovate-lanceolate to lanceolate, abaxial surface glabrescent. Stipules without a minute globose gland (colleter) at the apex. Pistillate flowers without nectary glands in place of petals. Fruits ellipsoid to rarely obovoid ................................................................................................................................................................. C. bonplandianus

- Young branches pubescent. Leaves chartaceus, ovate to cordate, abaxial surface pubescent. Stipules with a minute globose gland (colleter) at the apex. Pistillate flowers with nectary glands in place of petals. Fruits obovoid ................................... C. gracilipes

21. Trees. Adaxial leaf surface with hispid indumentum. Fruits conspicuously muricate ............................................... C. floribundus

- Shrubs to subshrubs. Adaxial leaf surface glabrous or other type indumentum. Fruits smooth .................................................... 22

22. Staminate flowers reduplicate-valvate. Styles multifid ..................................................................................................... C. tricolor

- Staminate flowers valvate. Styles bifid, twice bifid or tetrafid ...................................................................................................... 23

23. Columella apex with three inflated lobes ....................................................................................................................................... 24

- Columella apex inconspicuous and unlobed .................................................................................................................................. 26

24. Shrubs 1-2 m tall, densely branched, stems striate .............................................................................................................. C. fulvus

- Subshrubs to shrubs up to 50 cm tall, little branched, stems smooth ............................................................................................. 25

25. Stipules narrowly lanceolate with numerous glands (colleters). Staminate bracts narrowly lanceolate .................... C. grandivelus

- Stipules glanduliform, with 5 glands (colleters). Staminate bracts ovate or lanceolate ............................................. C. subvillosus

26. Leaves adaxial surface with lepidote subentire trichomes ......................................................................................... C. myrianthus

- Leaves adaxial surface glabrous or with stellate or appressed-stellate trichomes .......................................................................... 27

27. Leaves venation hyphodromous (only midrib visible) ............................................................................................. C. serpyllifolius

- Leaves with other venation type ..................................................................................................................................................... 28

28. Indumentum yellowish to orange. Stipules reduced to minute conic glands (colleters). Staminate petals cream with a central dark line ............................................................................................................................................................................. C. chamaepitis

- Indumentum whitish, yellowish, cinereous, silvery, cream or ferrugineous. Stipules inconspicuous, not reduced to glands (colleters). Staminate petals cream or white without a central dark line .......................................................................................................... 29

29. Leaves up to 1.5 cm long. Styles twice bifid ......................................................................................................... C. pycnocephalus

- Leaves 3 cm long or longer. Styles bifid or tetrafid ....................................................................................................................... 30

30. Leaves with abaxial surface covered by lepidote subentire or stellate-lepidote trichomes. Styles bifid ....................................... 31

- Leaves with abaxial surface covered by stellate trichomes. Styles tetrafid ................................................................................... 33

31. Leaves adaxial surface glabrous. Pistillate flowers subcampanulate ............................................................................................. 32

- Leaves adaxial surface pubescent, rarely glabrescent. Pistillate flowers rotate ............................................................................. 33

32. Leaf blade narrowly elliptic to narrowly lanceolate. Inflorescences unisexual ...................................................... C. uruguayensis

- Leaf blade broadly ovate, broadly elliptic or rarely obovate. Inflorescences bisexual ........................................... C. muellerianus

33. Abaxial leaf surface covered by stellate-lepidote trichomes; secondary veins conspicuously raised ................... C. ceanothifolius

- Abaxial leaf surface covered by lepidote subentire trichomes; secondary veins inconspicuous, not raised .................................. 34

34. Leaf blade narrowly elliptic to broadly elliptic. Pistillate sepals obovate to widely elliptic. Ovaries and fruits globose. Seeds brown without spots ................................................................................................................................................................ C. splendidus

- Leaf blade narrowly lanceolate to lanceolate. Pistillate sepals narrowly spatulate. Ovaries and fruits ellipsoid. Seeds gray with brown spots ................................................................................................................................................................ C. longicarpus

35. Bracts with glands (colleters), viscid. Staminate flowers without cucullate sepals. Pistillate sepals equal, entire or slightly laciniate ........................................................................................................................................................................................... 36

- Bracts without glands (colleters), not viscid. Staminate flowers with 3 cucullate sepals. Pistillate sepals unequal (3 conspicuous), pinnatifid ......................................................................................................................................................................................... 40

36. Leaves with lanate indumentum, margin entire. Inflorescences densely congested ................................................. C. heterodoxus

- Leaves pubescent, margin entire to serrate. Inflorescences lax. ..................................................................................................... 37

37. Stipules with glands (colleters) along the margin ..................................................................................................... C. serratifolius

- Stipules with glands (colleters) only at the base ............................................................................................................................ 38

38. Leaves pubescent. Bracts lanceolate-rhombic. Pistillate sepals entirely covered by glands (colleters) ................. C. chaetophorus

- Leaves glabrescent to sparsely pubescent. Bracts lanceolate. Pistillate sepals with glands (colleters) along the margin or absent ... ......................................................................................................................................................................................................... 39

39. Leaves rhombic, rarely obovate, margin irregularly serrate. Inflorescences bisexual. Pistillate sepals entire, glands (colleters) along the margin ........................................................................................................................................................................... C. fuscus

- Leaves elliptic, rarely oblanceolate, margin entire. Inflorescences unisexual. Pistillate sepals slightly laciniate, without glands (colleters) ......................................................................................................................................................... C. calycireduplicatus

40. Subshrubs with xylopodium. Leaves with actinodromous venation. Bracts linear, entire. Plants from open vegetation and cerrado .................................................................................................................................................................................... C. didrichsenii

- Shrubs without xylopodium. Leaves with camptodromous venation. Bracts ovate, pinnatifid. Plants from edges of forest and disturbed areas ................................................................................................................................................................. C. triqueter