February 4, 2018

Edible Groundnuts (Apios sp.div.)

To genus Apios (family Fabaceae) belongs a few species of herbaceous climbers which are native to east Asia and North America. They all create underground tubers which are edible in case some of them. Especially 3 species are known to have delicious tubers and they are sometimes cultivated. 
An inflorescence of Apios fortunei (Japanese Groundnut)
Boiled tubers of two varieties of Apios tuberosa (American Groundnut)
The most known species is Apios tuberosa = A. americana (American Groundnut). It grows in wild state in North America and is cultivated in numerous varieties worldwide (but rarely). It is frost hardy perennial. Some accessions are hardy to less than -30C degree (=-22F degree), but other southern varieties are less frost resistant. It can be propagated by seeds (only these ones which bloom and creates seeds) or only by tubers. One plant creates very numerous tubers on long rhizomes. They have very good taste when boiled or baked and very soft skin (they do not need be peeled). The seeds and young seed-pods are also edible after cooking.  The forms which bloom have very ornamental flowers in medium size inflorescences (but my plants have not flowered so I have not their photo). I grew two varieties: one unnamed, but improved from Virginia (climber about 2-3m = 7-10ft tall, which creates large to medium size oblong tubers and is very frost hardy) and the second larger variety “Nutty” (large climber to 3-4m = 10-13ft tall in my zone 6b, roundish large or medium tubers, never flowering).

 Apios tuberosa (unnamed variety from Virginia) 

Young inflorescences

Apios tuberosa "Nutty"
This variety creates very tall annual shoots
and large roundish tubers

The second American species, very hard to find and rarely cultivated, is Apios priceana (Price's Potato-bean, Price's Groundnut, Traveler's Delight). This is very large (3-5 m = 10-16 ft tall) herbaceous climber which is much frost resistant and winters easily without mulching in my zone 6b. It is native to the U.S. states of Alabama, Mississippi, Kentucky, and Tennessee. It creates only one turnip-like rhizomatous tuber, which enlarges every year and can grow quite large in numerous years. The tuber is edible. It can be easily propagated by seeds (they can be sown direct in the garden after last frosts). It also has not flowered yet in my experience. 
Apios priceana
This species creates only 1 tuber per plant. It can be quite large after numerous years. On the photo there are 2 years old tubers
The third species which I grew is Asiatic Apios fortunei (Japanese Groundnut, Chinese Groundnut). In my experience my plants created also single tubers per plant, but with a few long stolons, so I suppose that this species is intermediate between previously described – creates a few tubers (not as numerous as A. tuberosa but not one as A. priceana). It is the only species which flowered freely in my cultivation. The flowers are lovely close up and curious but not very showy. I have not tasted the tubers of last two species yet, but they are described as delicious. It is probably full frost hardy in zones 5/6 but I have not wintered it outside yet. 
Apios fortunei
 Plants in late spring
 and in summer

 The inflorescences of this species are lovely close up but not very showy

The tubers with long stolons
 There exists a few other species of groundnuts (Apios spp.). If you have available seeds or tubers any of them please write to me.

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