Onagraceae Jussieu (1789: 317)

Luo, Yike & Xie, Lei, 2023, A checklist of Onagraceae in the Pan-Himalaya region, Phytotaxa 597 (4), pp. 245-268 : 246-247

Onagraceae Jussieu (1789: 317) , as “Onagrae”, nom. cons.

Type:— Onagra Miller (1754: 434) [= Oenothera Linnaeus (1753: 346) ].

= Epilobiaceae Ventenat (1799: 307) , as “Epilobianae”.

Type:— Epilobium L.

= Jussiaeaceae Martinov (1820: 350) , as “Jussieae”.

Type:— Jussiaea Linnaeus (1753: 388) .

= Circaeaceae Ruthe (1827: 137) , as “Circaeae”.

Type:— Circaea L.

Annual or perennial herbs in the Pan-Himalaya region. Leaves alternate to opposite, occasionally whorled; margin entire or serrate, petiolate to sessile. Flowers (2–)4(–5)-merous, actinomorphic or zygomorphic; floral tube present, or absent in Chamaenerion Séguier (1754: 168) , Ludwigia , nectariferous within; sepals valvate; petals one or two times as many as sepals, variously colored; stamens twice as many as sepals, the antisepalous set of stamens longer, rarely (in Chamaenerion ) all equal, or as many as sepals; ovary inferior, ovules 1 to numerous in 1 or several rows; style 1, stigma with lobes or not. Fruit a loculicidal capsule. Seeds small, smooth or papillose, anatropous; endosperm absent. Base chromosome numbers: x = 7, 8, 15, and 18 ( Wagner et al. 2007).

Key to genera of Onagraceae in the Pan-Himalaya region

1 Sepals 2; fruit bristly with hooked hairs.................................................................................................................................. Circaea

- Sepals more than 2; fruit not bristly with hooked hairs......................................................................................................................2

2 Seeds with a coma of hairs .................................................................................................................................................................3

- Seeds lacking a coma of hairs ............................................................................................................................................................4

3 Leaves spirally arranged or alternate; petals entire; stigma deeply 4-lobed ............................................................... Chamaenerion

- Leaves opposite, or alternate in inflorescence; petals 2-lobe; stigma entire or 4-lobed...................................................... Epilobium

4 Sepals persistent after anthesis; floral tube inexistence ........................................................................................................ Ludwigia

- Sepals deciduous after anthesis; floral tube existence, often well beyond ovary................................................................ Oenothera