Commelina, Linnaeus, 1753

Maldonado-Moreno, Claudia, Alvarez-Jiménez, Abel De Jesús, Gutierrez, Héctor David Juárez-, Alba, Guillermo Alatorre-De & Muñiz-Castro, Miguel Ángel, 2023, A remarkable new species of Commelina (Commelinaceae) from western Mexico, Phytotaxa 612 (1), pp. 67-76 : 74

Identification key to Commelina occurring in western Mexico

1. Spathe base free, cordate ...................................................................................................................................................................2.

- Spathe base connate, truncate............................................................................................................................................................9.

2. Petals equal or subequal ....................................................................................................................................................................3.

- Petals strongly unequal......................................................................................................................................................................7.

3. Petals flesh-coloured to buff orange..................................................................................................................................... C. scabra

- Petals blue to lilac, rarely white ........................................................................................................................................................4.

4. Plants normally up to or exceeding 1 m, robust; leaves (rarely 1.5 in C. jaliscana ) 2–4.5 cm wide................................................5.

- Plants up to 90 cm; leaves less than 2 cm wide.................................................................................................................................6.

5. Leaves glabrous; spathes obtuse or shortly acuminate at apex, upper cincinnus included in the spathe.......................... C. coelestis

- Leaves scaberulous; spathes acuminate to long acuminate at apex, upper cincinnus exserted from the spathe.............. C. jaliscana

6. Leaves narrowly lanceolate to linear, conduplicate; spathes acuminate to long acuminate, usually glabrous (rarely pubescent) ...... ...................................................................................................................................................................................... C. dianthifolia

- Leaves lanceolate to oblong-lanceolate, flat; spathes acute, usually pubescent (rarely glabrescent) ............................... C. tuberosa

7. Plant creeping to ascending, stems slender; inflorescence peduncle 5–20 mm long ........................................................... C. diffusa

- Plant erect or decumbent, stems robust; inflorescence peduncle 10–40 mm long............................................................................8.

8. Fruits indehiscent, blue to dark purple when mature ....................................................................................................... C. leiocarpa

- Fruits dehiscent, brown when mature.............................................................................................................................. C. texcocana

9. Petals subequal, concolourous.........................................................................................................................................................10.

- Petals strongly unequal, discolourous .............................................................................................................................................11.

10. Leaves narrow, often linear, scabrous; inflorescences apparently terminal, peduncle 1–2.5 cm long, spathe 2–2.5 × 1–1.3 cm, scabrid-hirtellous ............................................................................................................................................................... C. standleyi

- Leaves broad, lanceolate, oblong-lanceolate, elliptic-lanceolate or ovate-lanceolate, glabrous; inflorescences leaf-opposed, peduncle 2.5–6.5 cm long, spathe 3–4.5 × 2–3 cm, glabrous, glaucous ............................................................................. C. occulta

11. Leaf-sheaths auriculate, with white hairs; petals sky blue to pale blue, rarely white or lilac; fruit dehiscent, brown when mature... ............................................................................................................................................................................................... C. erecta

- Leaf-sheaths entire, with rusty hairs; petals white; fruit indehiscent, white when mature ............................... C. rufipes var. rufipes