Victoria cruziana A.D.Orb.

Frontiers in Plant Science

Type

Bolivia [Argentina], Corrientes, banks of the Paraná river, Arroyo de San José, beginning of 1827, d’Orbigny s.n. (lectotype: P (P02048598∗) (designated by de Lima et al., 2021); isolectotypes: P (P02048599).

Vernacular

Irupé (yrupé), yacare yrupé, naanók lapotó (poncho del otany), maíz de agua, Santa Cruz Waterlily, Victoria regia.

Morphology Leaves

Leaves up 2.4 m broad, adaxial surface of lamina green, abaxial surface of lamina green or dark blue-green, radial and reticulate ribs yellow or green; leaf margins form a high rim 8–10% of leaf length, rim ± perpendicular to or slightly recurved over adaxial surface at base, flared outwards at top (sigmoid in profile), abaxial surface of rim green or tinged maroon, hairs 1–3 mm, simple, multicellular, 10–15 segmented

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary 7–10 cm diameter, outer surface covered in prickles 1–22 mm (dried), prickles abruptly tapering from c. half their length to sharp apex; hairs absent or present, where present 0.1–12 mm; inner surface of ovary with moderately concave stigmatic surface, rounded to triangular in longitudinal profile, ridged with lines corresponding with 25–38 radially arranged locules, each containing 20–25 ovules 1.5–1.8 mm (fresh)

Morphology Reproductive morphology Flowers Tepal

Inner tepals 7–10 × 1.5–9 cm (fresh), innermost all white both in bud and during first-night anthesis, crinkled in appearance, turning pale to dark pink on second-night; outer staminodia, 6– 7 × 1–1.5 cm, thick, rigid, apiculate; stamens 4–6 × 0.5–1 cm inner staminodia > 50, 4–6 × 0.5 cm; base of lower parts of carpellary appendage flat, arising from stigmatic surface at 45 degree angle, cuneate, length of upper parts not exceeding that of lower parts At first night anthesis, inner tepals have a crinkled appearance. Outer tepals 4, 10–13 × 4–9 cm when fresh, abaxial surface green and/or tinged maroon abaxially prickles absent or present, where present up to 100 per tepal, prickles tapering abruptly at their midpoint to a sharp point, 1–10 mm (dried), distributed up to lower one third of surface, hairs absent or present, where present 0.1–1 mm

Morphology Reproductive morphology Flowers

Flower at first night of anthesis: all inner tepals white, outer staminodia tipped pink; at second night anthesis, outer tepal adaxial surface pink, inner tepals pale or dark pink at base, white or pink towards apex, outer staminodia dark pink for basal two-thirds of their length, white then pink towards apex, inner staminodia pink at base Flower bud broadly ovoid, concave just before apex, up to 30 cm diameter at second- night anthesis

Morphology Reproductive morphology Seeds

Seeds, c. up to 1000 per fruit, 7–9 × 8–10 mm, globose, raphe faintly visible, brown to black, surrounded by a mucilaginous aril.

Distribution

Victoria cruziana is restricted to the Paraná river basin and tributaries, from Paraguay to Argentina, and possibly Bolivia.

Conservation

Based on the maximum potential habitat of wetlands (including Esteros de Ibera National Park Wetlands) and a combination of verified herbarium collections and iNaturalist images we estimate the EOO of V. cruziana to be between 46,563 and 132,945 km2. This exceeds the threshold for a threatened category under criterion B (IUCN Standards and Petitions Committee, 2019). We calculate the AOO to be 120 km2, although an upper estimate based on the extent of the river may exceed 2,000 km2 (but not more than 3,000 km2). This would assess V. cruziana as between Endangered and Vulnerable categories. There are more than 10 locations but no information about population fragmentation. We infer a continuing decline in habitat quality due to the increasing frequency of droughts, the abstraction of water, deforestation (Caivano and Calatrava, 2021; Comisión Nacional de Actividades Espaciales, 2021) and big hydroelectric dams. For example, Itaipu is one of the largest dams in the world (Stevaux et al., 2009) and lies within the V. cruziana range. Whilst the AOO upper estimate is close to the threshold for VU, there are more than sufficient criteria for a threatened category under criterion B, and we therefore assess V. cruziana as LC. We recommend further documentation of the distribution and size of V cruziana populations and investigations into their fluctuation through time as we believe that it may be vulnerable to an increase in the frequency and severity of droughts associated with climate change and increased sedimentation caused by the construction of large dams within its habitat (Stevaux et al., 2009).

Recognition

Victoria cruziana forms the proportionately highest leaf rims of all the species, and these are always slightly recurved over the flat part of the lamina, flaring out at the top. The concavity of the outer tepals before their apex gives the bud a pinched-in appearance. Prickles are absent or occur on the outer tepal abaxial surface, but only up to one-third of their length from the base. In this species, hairs which are sometimes present on the lower outer tepal abaxial surface and ovary are the only ones large enough to see without magnification.

Use

Ornamental.