Calea, Linnaeus, 1763

Bueno, Vinicius R., Cassol, Ana P. V., Leroy, Carolina J., Bueno, Marcelo L. & Heiden, Gustavo, 2023, Calea × crassa (Neurolaeneae: Asteraceae), a new nothospecies from Paraná state, Brazil, Phytotaxa 618 (2), pp. 133-148 : 142-143

Identification key to the taxa of the Monocephala clade of Calea

1. Blade leaf 0.7–2.6 mm wide, ovate, margins thickened, pale olivaceous, serrate with mucronate teeth; 30–100 disc florets per capitulum ...........................................................................................................................................................................................2.

- Blade leaf 0.05–0.5 mm wide, linear, margins thin, olivaceous, entire; 3–15 disc florets per capitulum.........................................4.

2. Third series of phyllaries foliaceous, sometimes apex foliaceous, fifth series of phyllaries with obtuse apex ......... Calea × crassa .

- Third series of phyllaries scarious, fifth series of phyllaries with rounded apex ..............................................................................3.

3. Leaves discolorous, abaxial surface hispid, rarely glabrous to sparsely hispidulous, if glabrous then with surface glandular-punctate; outermost series of phyllaries densely hispid to hispid, sometimes hispid to sparsely hispid; cypselae 2–2.5 mm long.................... .......................................................................................................................................................................................... Calea ilienii

- Leaves concolorous, abaxial surface glabrous, sometimes sparsely puberulent or glabrous to sparsely hispid, if sparsely hispid then with surface glands absent; outermost series of phyllaries glabrous, rarely glabrous with base sparsely hispid; cypselae 3.2–3.6 mm long....................................................................................................................................................................... Calea monocephala

4. Plants 0.15–0.4 mm tall, abaxial surface glandular-punctate; peduncle 12–16 cm long, outermost series of phyllaries foliaceous; disc floret tube 1.7–2.4 mm long, cypselae 3–3.6 mm long, pappus scales 15–16.................................................. Calea abbreviata

- Plants 0.5–0.8 mm tall, abaxial surface eglandular; peduncle 20–23 cm long, outermost series of phyllaries scarious; disc floret tube 1–1.5 mm long, cypselae 4–4.5 mm long, pappus scales 8–12......................................................................... Calea kirkbridei