TABLE 1.
Summary of the information including seed oil content, NA and EA content, and NA production limitations on the main plant seeds rich in NA.
| Species | Common name | Oil content (%) | NA content of total fatty acid (%) | EA content of total fatty acid (%) | Distribution | Problems | References |
| Malania oleifera Chun et S. K. Lee | / | 58.0∼63.0 | 55.7∼67.0 | ∼13.1 | Western Guangxi and southeast Yunnan, China | Rare, endangered, narrow distribution | Wang et al., 2006; Tang et al., 2013; Li et al., 2019; Xu et al., 2019 |
| Ximenia caffra Sond. | Sour Plum | 40.1∼65.0 | 5.9∼11.4 | ∼0 | Tanzania, Zambia, Zimbabwe, Botswana, Namibia, Mozambique and South Africa | Lignoceric acid needs to be separated from NA | Lee, 1973; Venter and Venter, 1996; Chivandi et al., 2008 |
| Acer truncatum Bunge | Purpleblow maple | 45.0∼48.0 | 3.9∼7.8 | ∼17.0 | North China, Japan, and Korea, North America and Europe | Eight to ten years to maturity | Appelqvist, 1976; Jart, 1978; Taylor et al., 2009; Qiao et al., 2018; Ma et al., 2019, 2020 |
| Xanthoceras sorbifolia (Xanthoceras sorbifolium Bunge) | Yellowhorn | 63.3∼69.5 | 2.0∼2.6 | 8.3∼8.5 | North and Northeast China | Narrow distribution, a unique species in China | Zhang et al., 2017; Li et al., 2019; Liang et al., 2019 |
| Borago officinalis L. | Borage | 30.0∼40.0 | ∼1.5 | 1.5∼3.5% | Originated in Iran and some Mediterranean countries of West Asia, now in almost all over the world | Seeds shattered when mature | Appelqvist, 1976; Jart, 1978; El-Din and Hendawy, 2010; Hashemian et al., 2010 |
| Cannabis sativa L. | Hemp | 26.3∼37.5 | 3.0∼8.0 | 1.0∼14.0 | Originated in India, Bhutan and Central Asia, now in various countries | Risk of drug harm seriously restricts the cultivation | Appelqvist, 1976; Jart, 1978; Kriese et al., 2004 |
| Cardamine graeca L. | Bittercress | 12.0∼13.0 | 45.0∼54.0 | 9.3∼10.0% | Mediterranean countries | Narrow red soil requirements, seed shattering | Jart, 1978; Taylor et al., 2009 |
| Lunaria annua/Lunaria biennis L. | Honesty/money plant | 25.0∼35.0 | 14.0∼24.2 | 43.0∼50.0 | Europe to West Asia | A poor-yielding biennial, seed shattering | Mastebroek and Marvin, 2000; Taylor et al., 2009; Dodos et al., 2015 |
| Tropaeolum speciosum Poepp. & Endl. | Flame Flower | 12.3∼26.0 | 40.0∼45.4 | ∼17.0 | Rare plant growing in Chile | Difficult to obtain seeds and reproduce | Litchfield, 1970; Taylor et al., 2009; Li et al., 2019 |
| Tropaeolum majus L. | Nasturtium | 6.0∼10.0 | 1.0∼2.0 | 75.0∼80.0 | Originated in South America Peru, Brazil and China, now in temperate areas over the world | Low oil content, difficult to obtain seeds and reproduce | Taylor et al., 2009 |
NA, nervonic acid; EA, erucic acid.