- Cyrtosperma is a genus of flowering plants in the family Araceae.
- The genus has undergone considerable taxonomic changes in the 1980s, and is not considered native only to Southeast Asia and some Pacific Islands.
- Etymology: Genus name Cyrtosperma derives from Greek kurto-sperma, meaning curved seed, referring to the shape of the seed.
- Subfossil leaf fragments of giant swamp taro (Cyrtosperma chamissonis) were recovered from archaeological contexts dating as early as A.D. 1451.
- Giant swamp taro is the largest of the root crop plants known collectively as Taro, which are cultivated throughout Southeast Asia and the Pacific.
- Giant swamp taro may be field stored for very long periods - up to 30 years or more - and, as such, has been used as emergency crop in times of natural disaster and food scarcity.
Palauan has the habit of Alocasia macrorrhiza, a large plant with a very stout trunk, growing in dense clumps, . Leaves are very big, hastate, up to 1.5 meters in length. Petioles are large and stout, up to 2.5 meters long and 10 centimeters in diameter. Spathe is 30 to 60 centimeters long and oblong. Spadix is cylindric, about 15 centimeters long, 2 to 3 centimeters wide. Seeds are globose and about 5 millimeters wide.
Giant swamp taro may reach heights of 4–6 metres, with leaves and roots much larger than Colocasia esculenta. The sagittate leaves are up to 6' 7" (2 meters) long by up to four feet (120 cm) in width, borne atop petioles or stalks up to 19' 6" (6 meters) in length and four inches (10 cm) wide. It is relatively resistant to disease and pests but is susceptible to taro beetle (Papuana). The corm, which can reach weights of 80 kg or even 220 pounds (100 kg) with a diameter of up to 39 inches (1 meter) and equally long, is starchy and cream or pink in colour, with a taste similar to sweet potato, though it is drier in texture. (13)
- Native to the Philippines.
In ravines along streams in Luzon (Sorsogon), Mindoro, Samar, Leyte, Palawan and Mindanao.
- In some regions planted for its edible corms or as an ornamental.
- Also native to Borneo, Caroline Is., Cook Is., Fiji, Gilbert Is., Jawa, Malaya, Marshall Is., New Guinea, Samoa, Santa
Cruz Is., Society Is., Solomon Is., Sumatera, Vanuatu.
- Contains 62.61% moisture, 1.05% ash, 0.81% protein, 0.09% fat (ether extract), 33.87% carbohydrate, and 1.57% crude fiber providing 1,430 calories per kilo.
- Study reports the rootstock to contain 0.5% starch.
- Yellow-fleshed cultivars yielded
high carotenoid concentrations, substantial amounts of zinc, iron and calcium.
- In a study of 34 cultivars, ß-carotene varied from 50 to 4486 µg/100g; yellow-fleshed cultivars yielded higher carotenoid concentrations. Mineral content of ten cultivars yielded (wet weight basis) substantial concentrations of zinc (5.4-46.1 mg/100g), iron (0.3-0.8 mg/100g) and calcium (121-305 mg/100g).
(see study below) (6)
- Nutrient analysis per 100 grams of edible portion of corms
of Cyrtosperma chamissonis yielded 131 calories, 0.9 g protein, 31 g carbohydrate, 334 mg calcium, 56 mg phosphorus, 1.2 mg iron, 0.045 mg thiamin, 0.074 mg riboflavin, and 0.88 mg niacin. (7)
- Yellow (YP) and white (WP) sections of giant swamp taro (GST) yielded 40.0 g/kg and 51.5 g/kg (dry weight), respectively of pure mucilage made up of D-glucose (44.95-78.85%), D-galactose (8.70-25.35%), D-mannose (3.20-10.45%), D-arabinose (2.45-5.20%) and small amounts of glucoronic acid and rhamnose. (see study below) (10)
- Emmenagogue, ecbolic.
- Studies have shown antioxidant property.
- Plant contains calcium oxalate crystals which cause very unpleasant sensations of needles stuck in the mouth and tongue. They are easily neutralized by drying or cooking or by steeping in water. (8) (9)
Edibility / Nutrition
- Large rootstocks are eaten when food is scarce.
- Corms are edible: roasted, steamed or boiled.
- Used as fillings
for pastries like hopia.
- In the Pacific atoll islands, it is the most important staple food.
- Peeled and chopped stalks used in soups.
- Toxicity caution: Roots require hours of cooking to reduce toxicity in the corms.
- As a
staple food it is an important source of carbohydrates. Although rich in carbohydrates, it is poor in other constituents.
- Of limited medicinal use in the Philippines.
- Decoction of spadix used as emmenagogue and ecbolic.
- In Kirbati, Catala, yellow mold from sliced and sundried corms used to treat skin infections.
• Comparative Study of Alcohol Yield of Acid Hydrolyzates: Study evaluated the potential alcohol yields from the acid hydrolysis of corms of three araceae plants: gabi (colocasia esculenta) 35.90%, palauan (Cystrosperma merkusii) 21.93%, and San Fernando (Xanthoma sagittifolium) 26.73%. There were no significant differences in the theoretical alcohol yield. Results suggest a potential of utilizing the three plant types for alcohol production. (2)
• Carotenoid and Mineral Content of Cultivars: Giant swamp taro (Cyrtosperma merkusii) is an important food in the mountain islands of Micronesia. Study showed the cultivars to be rich in carotenoid concentration with substantial amounts of zinc, calcium, and iron. Cultivars were acceptable in taste and production factors. Study suggests promotion for its potential health benefits. (see constituents above) (6)
• Mucilage / Antioxidant Activity: Study investigated the mucilage profile and antioxidant properties of giant swamp taro tubers. Antioxidant activity of YP was higher than those of WP; chelating ability and reducing power increased with mucilage content. Effective concentration (EC50) of mucilages (WP 1.28 ± 0.05 mg/mL; YP 1.42 ± 0.04 mg/mL) were lower than that of citric acid. YP and WP mucilages are usually excellent sources of chelating agents. (see constituents above) (10)
• Fortified Swamp Taro Cookies: A fortified cookie from dehydrated swamp taro (ST, Cyrtospermma merkusii) combined with all-purposed enriched wheat flour was developed. Study evaluated unfortified ST, ST cookie with moringa oleifera leaves, ST with dehydrated moringa leaves and squash (Cucurbita moschata). Results showed the addition of dehydrated vegetables significantly increased the lipid, total mineral, and vitamin A content of the finished products, with a sensory evaluation that showed good market potential. (11)
• Daluga Corm Starch / Potential Food Source: Study evaluated daluga corm starch as potential food source in measures of starch yield, chemical composition, and granules morphology. Data shows daluga starch is unimodal with average size of 12.50 µM and crystalline type A. Average starch yield is 14.70%, with medium to low amylose content that assures a good mouthfeel taste. Findings support utilization of daluga starch as natural resource of food. (14)
• Nutrient and Carbohydrate Profile / Wild and Cultivated Varieties: Study evaluated cultivated and wild varieties of giant swamp taro for nutrient, phytochemical and carbohydrate profile and storage stability of its flour. Boiled cultivated and wild varieties yielded energy contents of 385.67 kcal and 377.29 kcal, respectively. Beta carotene and vitamin C contents of boiled and flour products from wild variety were significantly higher than cultivated variety. Processed products of both local taro varieties had >75% antioxidant activity. Boiled and floured cultivated taro contained significantly higher amounts of amylose, dietary fiber, and resistant starch compared to wild variety. Glycemic index of processed taro from two local varieties had a range of 64-70% (intermediate). (15)