Chinese Giant Arrow Head (Sagittaria trifolia var. edulis)

Giant Arrow Head, Chinese Arrow Head – Sagittaria trifolia var. edulis (syns. S. trifolia subsp. leucopetala, S. edulis) this is a shallow water/bog large perennial herb which creates in autumn giant tubers (in size to 5-10 × 4-6 cm = 2-4 x 1,5-2,5 inch) which are edible after cooking (delicious). 

The tubers can be huge (the coin on the photo is size about 1 inch=2,5cm)

It is said to be hardy to frost to about -10 C degree = 14 F degree [in winter 2016/17 the tubers have survived a permanent frost about -1 C degree (= 30 F degree) by about 1,5 months and occasionally lower temperatures, when they were stored in my cool cellar in moist sand in large glass jar; in next winter a few small tubers survived outside when depply buried in soil (about 15-20cm = 6-8inch deep) in open garden in light moist (but not wet) soil, when the temperatures were bellow -20C degree = -4F degree]. It is cultivated in Japan, Korea and China as root vegetable. Can be easily grown in large (at least 25l = 7 gallons) containers. The tubers should be planted direct outside in April-May. The crop can be harvested in September-October. In my experience this plant has not flowered at all, but the huge leaves have very exotic and ornamental look. Easy to growing in summer season in my 6b zone – it does not need much of attention [needs only much of water - it enough about 5-30 (60)cm = 2-12(24)inch above soil surface (but can survive occasional lower water level), regular fertilize and (almost-)full sunlight]. The tubers are also easy to storing in winter. The best use glass jar (to protect them against mice) and moist sand but in the cap of the jar should be made a holes to tubers could respire and do not die.

The tubers are especially delicious when candied and stored by some time to they pass by sugar/honey and become soft inside (they are ready after a few months of cool storage). Such prepared ones tastes as “delicious nuts”.  The leaves and young shoots are aslo said to be edible. It is also used in folk medicine.  

It usually not blooms but the leaves are very ornamental and large

The tubers can be planted densely if you use large container

There exists numerous Arrow Head species worldwide. Almost all of them (if not all) are edible. If you have seeds or tubers any exotic species (it can be common in wild state in your area) please write to me.