Key to the Species of Montanoa
1. Mature pales indurate, parallel-veined, broadest at base, apex sometimes recurved or reflexed, persistent on receptacle; pales at anthesis with apex as long as or longer than base, usually visible prior to anthesis; Mexico and Central America. [subgenus Monanoa.]
2. Pales densely glandular, long-pilose, prior to anthesis not longer than florets; disc florets usually 8-9 (occasionally 3-17); ligules usually (0-)3-5(-6), 3-9 mm long. [section Montanoa.] l. M. tomentosa.
2. Pales glabrous to sparsely glandular and/or short pilose, prior to anthesis longer than florets; head appearing spiny; disc florets mostly 30-150 (11-20 in M. revealii); ligules usually 8 or more (3-5 in M. revealii), 9.0-35.0 mm long. [section Echinocephalae.]
3. Mature pales 14-22 mm long, spreading upper section much exceeding folded basal portion (usually around ¼ folded); anthers and styles with at least apices black.
4. Disc florets 11-20; ray florets 3-5; disc florets as well as mature pales spreading outward, giving the head a stellate appearance. 9. M. revealii.
4. Disc florets 60-150; ray florets 10-15; disc florets as well as mature pales erect, not spreading.
5. Petiole conspicuously winged, sparsely puberulent; leaf blades often deeply lobed; mature pales 10-16 mm long. 7. M. liebmannii.
5. Petioles wingless, long-pilose or hispid; leaf blades cordate or ovate-triangular, unlobed; mature pales 15-22 long. 8. M. echinacea.
3. Mature pales 9-15 mm long with the spreading upper portion shorter than or as long as the folded basal portion (usually over 1/2 folded); anthers and styles with yellow apices.
6. Disc florets 25-50, corollas 4.0-5.0 mm long.
7. Anthers fully exserted from the corolla at anthesis; disc corolla, anther and stigma apices yellow but often tinged with purple; style and anthers more than 9 mm long. 5. M. andersollii.
7. Anthers not fully exserted from the corolla at anthesis; disc corolla, anther and stigma apices completely yellow; style and anthers less than 7 mm long. 6. M. standleyi.
6. Disc florets 70-150, corollas 6.0-7.0 mm long.
8. Stems purple, glabrous; mature pales 10-15 mm long; receptacle strongly convex, 3-4 mm tall, 1.5-2 mm wide; disc florets green or cream, more than 100; abaxial surface of leaves green. 2. M. frutescens
8. Stems green, pubescent; mature pales 9-11 mm long; receptacle about as tall as wide; disc florets yellow, fewer than 100; abaxial surface of leaves white pubescent.
9. Tree; petioles wingless and without auricles; apex of phyllaries rounded. 3. M. guatemalensis.
9. Shrub; petioles completely winged and auriculate; apex of phyllaries acute or acuminate. 4. M. mollissima.
I. Mature pales papery, net-veined, broadest near apex, deciduous with achenes, apex straight, never reflexed or recurved, curled in one taxon (M. leucantha subsp. arborescens;pales at anthesis with apex shorter than base, rarely visible prior to anthesis (except in some South American taxa); Mexico, Central and South America. [subgenus Acanthocarphae.]
10. Disc corollas 6.5-9.5 mm long, plants of Mexico and Central America.
11. Anther thecae black; disc corolla glandular and pubescent throughout; mature pales 8-12 mm long, with distinct apical sinus. 21. M. laskowskii.
11. Anther thecae yellow or brown; corolla glabrous or pubescent only at apex; mature pales over 15 mm long, without distinct apical sinus.
12. Petioles broadly winged to base.
13. Cymes in open usually leafless panicles, lateral branches mostly I-headed, longer than subtending leaves; disc florets 140-160; achene pubescent at apex; phyllaries 9-16(-22). 23. M. speciosa.
13. Cymes clustered at tips of leafy branches, lateral branches mostly several headed, shorter than subtending leaves; disc florets 65-95; achenes glabrous; phyllaries 7-10. 22. M. grandiflora.
12. Petioles with auricles but otherwise mostly without wings.
14. Phyllaries 10-12 mm long, longer than disc floret buds and overlapping; leaves medium green, shallowly lobed with small leaf-like appendages on petiole; corollas in bud moderately pubescent at apex with soft hairs; upper parts of stems terete; mature pales 15 mm long, base completely surrounding the achene. 24. M. imbricata.
14. Phyllaries 6.0-8.5 mm long, shorter than disc floret buds; leaves dark green, usually deeply pinnately or bipinnately lobed, bearing two auricles at base, petiole wingless; corollas in bud densely pubescent at apex with stiff interlocking hairs; upper parts of stems quadrangular; mature pales 16-22 mm long, base with achene partially exposed. 25. M. bipinnatifida.
10. Disc corollas 2.0-4.75 mm long; plants of Mexico, Central and South America.
15. Heads erect throughout development; mature pales straw-colored, never purple; plants of South America.
16. Ray florets 12-15; disc florets 40-75; style apex yellow.
17. Apex of pales truncate with 2 mm long, narrow, apiculate tip; scandent shrub; cymes in oppositely branched panicles on long slender branches; achenes 3.5 mm long. 11. M . fragrans.
17. Apex of pales gently tapering to a short, broad tip; erect shrubs; cymes in irregularly branched compound dichasia on short thick branches; achenes 2.5-3.0 mm long. 10. M. ovalifolia.
16. Ray florets 6-8; disc florets 90-135; style apex with black spots.
18. Pales with deep apical sinus (2 mm deep at maturity), margins irregular; achenes 3.5 mm long; upper stems purple, synflorescence a group of irregular cymes with heads tightly clustered on short peduncles; tree. 14. M. josei.
18. Pales without apical sinus, margins entire; achenes 1.0-2.5 mm long; upper stems green; synflorescence with cymes at ends of long slender branches of oppositely branched panicles; tree or shrub.
19. Shrub; leaves (including petiole) 7-16 cmlong, blades ovate-Ianceolate to rhombic, unlobed; ligules 6-10 mm long. 12. M. angulata.
19. Tree; leaves (including petiole) 20-90 cm long; blades ovate, often shallowly to deeply lobed; ligules 12.5-13.0 mm long. 13. M. quadrangularis.
15. Heads pendulous at late anthesis arid in fruit; mature pales straw-colored or purple; plants of Mexico and Central America.
20. Disc florets 85-120, corollas 2-3 mm long; plants of Central America.
21. Leaf-margins usually deeply and irregularly 3-5-lobed, irregularly dentate, abaxial surface densely white-pubescent, petiole with two distal auricles; achenes sculptured, 3 mm long; erect shrubs. 19. M. hibiscifolia.
21. Leaf-margins unlobed to shallowly and regularly 3-lobed, entire to serrate, abaxial surface green, petiole with or without auricles, with or without broad wings; achenes smooth, 2.0-2.5 mm long; shrubs or vines.
22. Petioles sometimes auriculate but otherwise unwinged; apices of disc florets, styles and anthers yellow; ligules of ray florets 12-24 mm long; disc corollas 2 mm long. 17. M. atriplicifolia.
22. Petioles both auriculate and winged to base; apices of disc florets, styles and anthers with black areas; ray florets 10-12 mm long; disc corollas 2.5-3.0 mm long. 18. M. petropoda.
20. Disc florets 23-60, corollas 3.5-4.75 mm long; plants of Mexico and Guatemala.
23. Three main veins of leaf branching at base of laminar portion of blade, petiole unwinged and without auricles; mature pales 7.5-10.0 mmlong with deep sinus (2 mm deep at spine); disc florets 20-35. 16. M. karwinskii.
23. Three main veins of leaf branching above base of laminar portion of blade, petiole at least partially winged, usually auriculate; mature pales usually over 10 mm long (8-17), apex usually tapering, without sinus or with sinus less than 1 mm deep; disc florets 30-60.
24. Tree; mature pales with apex truncate or sloping, sinus present; achenes 3-4 mmlong, sculptured; apex of style black; disc corollas green turning yellow. 20. M. hexagona.
24. Shrub; mature pales with apex tapering, sinus absent; achenes 2-3 mm long, surface smooth; apex of style yellow; disc corollas yellow. 15. M. leucantha
Montanoa supergroup (subgenus Montanoa)
Montanoa group (section Montanoa)
1. M. tomentosa
Frutescens supergroup (section Echinocephalae)
Frutescens group (series Frutescentes)
2. M. frutescens
3. M. guatemalensis
4. M. mollissima
5. M. andersonii
6. M. standleyi
Liebmannii group (series Amoenae)
7. M. liebmannii
8. M. echinacea
Revealii group (series Apertae)
9. M. revealii
Ovalifolia supergroup (subgenus Acanthocarphae)
*Ovalifolia group (series Ovalifoliae)
10. M. ovalifolia
II. M. fragrans
*Quadrangularis group (series Quadrangulares)
12. M. angulata
13. M. quadranglilaris
14. M. josei
* Arborescens supergroup
Arborescens group (series Hibiscifoliae)
IS. M. leucantha
* Karwinskii group
16. M. kanwinskii
17. M. atriplicifolia
18. M. pteropoda
19. M. hibiscifolia
20. M. hexagona
Laskowskii group (series Intermedieae)
21. M. laskowskii
Grandiflora group (series Grandiflorae)
22. M. grandiflora
23. M. speciosa
24. M. imbricata
25. M. bipinnatifida