Callitriche, von Linne, 1753

Lansdown, Richard V., Rhazi, Laila, Saber, Er-Riyahi, Madihi, Mohammed El & Grillas, Patrick, 2022, The genus Callitriche (Plantaginaceae, Callitricheae) in Morocco, Phytotaxa 555 (1), pp. 53-72 : 67-68

Key to Callitriche species in Morocco

1. Fruit unwinged, outer edge of mericarps rounded..............................................................................................................................2

- Fruit with an obvious wing.................................................................................................................................................................3

2. Pollen and therefore anthers yellow; leaves connate, at least apical leaves with more than one vein ....................6. C. obtusangula

- Pollen translucent, anthers colourless sometimes appearing whitish; leaves not connate, no leaves with more than one vein .......... .....................................................................................................................................................9a. C. truncata subsp. occidentalis

3. Pollen translucent, anthers colourless and typically very difficult to locate ......................................................................................4

- Pollen and therefore anthers yellow, anthers usually obvious............................................................................................................7

4. Leaves connate; styles reflexed with remains ultimately appressed to groove between mericarps of fruit; fruiting pedicel ≤ 12 mm; at least some upper leaves usually with more than one vein..............................................................................................................5

- Leaves not connate; styles erect or spreading; fruiting pedicel ≤ 1 mm; all leaves with only one vein ............................................6

5. Fruit ± isodiametric; wing narrow, with smooth margin.......................................................................... 1a. C. brutia subsp. brutia

- Fruit wider than long; wing broad, with irregular margin.................................................................. 1b. C. brutia subsp. naftolskyi

6. Wing of fruit broad, as wide as ovule or nearly so......................................................................................................4. C. lusitanica

- Wing of fruit very narrow, appearing as a rim around the mericarps............................................... 9b. C. truncata subsp. truncata

7. Mature fruit blackish ..........................................................................................................................................................................8

- Mature fruit brownish or grey-brown.................................................................................................................................................9

8. Fruit distinctly wider than long; filaments <0.2 mm, anthers typically low in leaf axils and difficult to locate; plants monoecious with most leaf axils containing both ♂ and ♀ flowers.................................................................................................... 3. C. deflexa

- Fruit ± isodiametric or slightly longer than wide; filaments erect <3.5 mm and anthers typically held clear above floating or terrestrial leaves; plants dioecious or predominantly of one gender, flowers solitary .................................................. 5. C. mathezii

9. Fruit <1.4 mm wide, wider than long on pedicel ≤ 55 mm ......................................................................................7. C. regis-jubae

- Fruit ≥ 1.4 mm diameter, ± isodiametric, ± sessile ..........................................................................................................................10

10. Testa cribrose; larger leaves with ≤ 17 parallel veins.................................................................................................... 2. C. cribrosa

- Testa in loops; largest leaves with no more than seven parallel veins ......................................................................... 8. C. stagnalis