Callitriche deflexa A.Braun ex Hegelmaier (1864: 58)

Lansdown, Richard V., 2022, The genus Callitriche (Plantaginaceae, Callitricheae) in Australasia and Oceania, Phytotaxa 547 (3), pp. 243-284 : 258

9. Callitriche deflexa A.Braun ex Hegelmaier (1864: 58)

≡ Callitriche deflexa var. brauniana Hegelmaier (1867: 15)

Type: — BRAZIL. RIO DE JANEIRO: 1859, F. Rudio s.n. (lectotype [designated by Lansdown & Hassemer 2021]: STU 15655!; isolectotypes G, GH 00048927 !, GH 00048928 !, GH00048929 !, K 000470002!, MO 1913776!, MO 1913777!, STU 15662) .

Description (from Lansdown and Hassemer 2021):—Stem and leaf scales present. Leaf bases connate. Lingulate leaves unknown, expanded submerged or floating leaves unknown, leaves of terrestrial plants elliptic, (1–) 2–4 mm long × 0.8–2.3(–3.0) mm wide, 3-veined, petiole 0.5–2.0 mm long. Usually one ♂ and one ♀ flower together in most leaf axils, occasionally solitary. Bracts lacking. Styles recurved, caducous, ≤ 1.8 mm long. Filaments erect, of undehisced stamens ≤ 0.2 mm long, of dehisced stamens ≤ 0.5 mm long; anthers quadrilocular, 0.1–0.4 mm diameter; pollen yellow. Fruits with pedicel ≤ 6.6 mm long, not strumose, wider than high, black when mature, 0.5–1.0 mm long × 0.7–1.0 mm wide, wing up to 0.1 mm throughout.

Illustrations: —Plate 1169(13) in Fassett (1951); Figure 8 in Bacigalupo (1979). Figures on pages 140 and 141 in Lansdown (2008); Figure 1 (h) in Lansdown and Hassemer (2021). Fig. 1i .

Recognition: — C. deflexa can be distinguished from all other Callitriche species in the region by the small fruit, most or all of which are long-pedicellate, blackish when mature and wider than high (although some fruit may be almost isodiametric, combined with both ♀ and ♂ flowers at least in the upper axils.

Distribution: —Non-native to the region. Within the region, Callitriche deflexa is known only from flower beds in the Royal Botanical Gardens, Melbourne. Elsewhere, it is native to central South America in an area including southern Brazil, Paraguay, Uruguay and northern Argentina. It is also very widespread as a non-native, with records from Mauritius, Morocco (Cherrate Arboretum), Portugal, South Africa, Taiwan, Tanzania and the United Kingdom ( Ascension Island) ( Lansdown and Hassemer 2021). See map on page 147 in Fassett (1951).

Habitats and Ecology: —In its native range, this species occurs in low-lying, humid areas such as sandy beaches and dry river beds. Outside its native range it occurs in a wide range of seasonally or permanently moist conditions such as irrigated areas of nurseries, ornamental beds and greenhouses in botanical gardens, low lying disturbed soil in areas such as unmetalled parking areas and on roadsides. There are no elevation data available from its native range.

Conservation Status: —This species is widespread within its native range and there is no evidence that it faces any significant threats, it is therefore classed as Least Concern (LC) ( IUCN 2012).

Additional material studied:—For a list of confirmed material, see Lansdown and Hassemer 2021.

Figures

FIGURE 1. Fruits of Callitriche in Oceania and Australasia: a—C. antarctica, b—C. aucklandica, c—C. brachycarpa, d—C. brutia, e—C. capricorni, f—C. chathamensis, g—C. cyclocarpa i face on and ii end on, h—C. cycloptera, i—C. deflexa, j—C. fuliginea.

FIGURE 8. Dimensions of fruit of C. cyclocarpa and C. umbonata, numbers in brackets indicate the number of fruit measured, the line shows equal length and width