Nyctaginaceae, Juss.

Sandoval-Ortega, Manuel Higinio & Sánchez-Escalante, José Jesús, 2022, The family Nyctaginaceae (Caryophyllales) in Sonora, Mexico, Phytotaxa 575 (1), pp. 35-56 : 36-37

A key to the genera of Nyctaginaceae present in Sonora follows:

2 Flowers tubular, more than twice longer than the fruit ...................... Salpianthus Bonpland (in Humboldt & Bonpland 1808: 154)

- Flowers capanulate or urceolate, slightly longer than the fruit ................... Boldoa Cavanilles ex Lagasca (in Lagasca 1816: 9–10)

3. Shrubs, trees or scandent woody climbers, stems sometimes armed with stout spines, flowers unisexual ......................................... .......................................................................................................................................................... Pisonia Linnaeus (1753b: 1026)

- Herbs, shrubs or suffrutescent plants, stems unarmed, flowers bisexual ...........................................................................................4

4. Flowers surrounded by fused or free bracts that form an involucre; base of perianth hidden by involucre during anthesis.............5

- Flowers surrounded by free bracts that do not form an involucre, or absent; base of perianth uncovered during anthesis ..............6

5. Involucre with 3 free bracts................................................................................................................................................................7

- Involucre with ≥5 fused or free bracts................................................................................................................................................8

6. Anthocarp 3–5 ribbed or winged........................................................................................................................................................9

- Anthocarp 8–10 ribbed .....................................................................................................................................................................10

7. Flowers zygomorphic, 3 per involucre, simultaneous anthesis, appearing as a single flower, peduncles not elongating in fruit; fruits aerial .................................................................................................................................................... Allionia Linnaeus (1759: 890)

- Flowers actinomorphic, 1 per involucre, peduncles short in flower, elongating and pushing into ground in fruit; fruits hypogeal ... .............................................................................................................................. Okenia Schlechtendal & Chamisso (1830: 92–93)

8. Stems erect to decumbent; bracts 5, fused; flowers 1–3(6) per involucre........................................ Mirabilis Linnaeus (1753a: 177)

- Stems postrate to erect, bracts 5–10, free; flowers ≥ 10 per involucre .......................................... Abronia Jussieu (1789: 448–449)

9. Flowers <1 cm long; perianth narrowly funnelform; bracts usually deciduous................................ Boerhavia Linnaeus (1753a: 3)

- Flowers> 2 cm long; perianth campanulate or widely funnelform; bracts persistent ................ Acleisanthes Gray (1853: 259–260)

10. Inflorescences racemose; anthocarp gibbose.................................................................................. Cyphomeris Standley (1911: 428)

- Inflorescences umbellate; anthocarp not gibbose............................................................... Commicarpus Standley (1909: 373–374)