Threeleaf Arrowhead

It differs from the European and North Asian Sagittaria sagittifolia Linn. in having pure white petals with no basal purple spot, yellow rather than purple anthers, reflexed rather than spreading sepals and very acute rather than blunt tips to the basal lobes of the leaf which are often longer than the blade.

This species exhibits much variation in leaf shape and flower size etc. as is mostly the case with aquatic plants. These variants do not deserve taxonomic status.

The plant is cultivated in China and Japan for starch-containing tubers which have been used in a variety of cooked and fresh dishes for centuries. It was probably introduced by Chinese to Hawaii, Indonesia and the Philippines on account of its food value. Aerial parts are fed to cattle in parts of India and southeast Asia. It is not put to any use in Pakistan.

Aquatic, glabrous herb with thick stolons bearing tubers at tip. Leaves mostly emerged, upright, sagittate or somewhat hastate, blade ovate or linear-lanceolate, (5-6.5-) 8-17 cm long along midrib, (1.5-2.5-) 5-7 cm broad, acute, basal lobes triangular or linear-lanceolate, often longer than the blade, sharply acute; petiole 60-75 cm long, triangular. Inflorescence an unbranched scapose raceme, 30-50 cm long. Flowers in 2-6 whorls of (2-) 3 (-5) flowers each, unisexual, 1-2 cm across, white; pedicels 8-15 mm long, short in females; bracts triangular-ovate, 8-10 mm long, 3-4 mm broad, acute-acuminate. Sepals elliptic, 6-8 mm long, 5-6 mm broad, somewhat keeled, margins broadly membranous, reflexed in fruit. Petals broadly elliptic-suborbicular, 12-15 mm long 12-15 mm broad, white, without basal purple spot. Stamens c. 20, filaments lanceolate, 1.5-2 mm long; anthers yellow, oblong, as long as the filaments. Head of achenes subglobose, c. 1 cm across; achenes triangularly obovate, with laterally bent beak. c. 2-3 mm long, wings subcrenate to entire.

Temperate & subtropical regions of N. Hemisphere.

Distribution: Widespread from Iraq through Iran and West Pakistan eastwards to China, Malaysia and Japan; introduced and adventive in Australia, Hawaii, Fiji, Philippines, Borneo and Java.

600 m

Fl.Per.: April-September.

Flowering and fruiting from May to November

Sagittaria trifolia var. trifolia is close relative of Sagittaria trifolia var. sinensis, but differs from the latter in its inflorescences with only 1-3 branches at lowest whorls (vs. more than 3 branches), tubers 2-3 cm (vs. 5-10 cm).

Sagittaria trifolia is occurring in Anhui, Beijing, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Henan, Hubei, Jiangsu, Liaoning, Shandong, Sichuan, Taiwan, Yunnan, Zhejiang of China, most of Asia, Indonesia (Borneo, Java), Japan including Ryukyus, Korea, Philippines, Russia, Europe.

Phylogeographic pattern and demographic history of Sagittaria trifolia in the entire geographic range in China were inferred from chloroplast DNA (cpDNA) atpB-rbcL intergenic spacer sequences (Chen et al., 2008). Results shown twenty-seven haplotypes were characterized and two of them were widely distributed in the populations. In the minimum-spanning network, all tip haplotypes were unique to a particular population, while the interior nodes represented widespread haplotypes. Nested clade analysis (NCA) of cpDNA haplotypes indicated that long distance dispersal characterized the post-glacial recolonization of S. trifolia in China. No specific refugia areas were suggested because genetic differentiation was low among the sampled regions and among populations within regions although a large number of the haplotypes were unique to a single population. The present data support that the unique haplotypes in individual population most likely represent recent mutational derivatives after long distance dispersal rather than the relics in refugia.

Plants stoloniferous, stolons often ending in a tuber, tubers usually 2-3 cm. Leaves aerial at least when mature, sagittate, larger, middle lobe not linear, more than 1.5 cm wide, apex acuminate, lateral lobes 1-1.4 times as large as middle lobe. Inflorescences with only 1-3 whorls of branches at base; bracts free or connate toward base. Flowers unisexual. Female flowers on lower 1-8 whorls, with short pedicels; male flowers with pedicels 0.5-1.5 cm; sepals reflexed, ovate, 3-5 mm long, 2.5-3.5 mm wide. Petals obovate, ca. 2 times as large as sepals. Stamens numerous; anthers yellow. Achenes obliquely obovoid, 4.5-5.5 mm long, 4-5 mm wide, winged, with an erect, apical beak.

The chromosomal number of Sagittaria trifolia is 2n = 22 (Chen et al., 1986; Uchiyama, 1989; Daniela, 1997).

Growing in ponds, lakes, marshes, paddy fields and channels.

Sagittaria trifolia, the threeleaf arrowhead or Chinese arrowhead, is a plant species widespread across the wet areas in Europe and in much of Asia.