Jauari palm

The Essence

"Astrocaryum jauari is one of the most common palms of the Amazonian floodplain, forming extensive colonies along black-water rivers and lakes throughout the basin; it has been described as the most frequently encountered palm in the flooded vegetation of the Rio Negro in Brazil. Its flood tolerance is exceptional. Piedade, Parolin and Junk (2006) found it spanning the entire flooding gradient, tolerating flood durations between 30 and 340 days, and Useful Tropical Plants records young plants surviving up to 300 days submerged per year. What sets the species apart is dispersal by fish. Fruit fall is annual and synchronised with high water, producing about 1.6 tonnes of fruit per hectare, and at least 16 fish species from five families - mainly Characidae - feed on the crop: 10 act as dispersers, three destroy the seed. Water-borne dispersal is negligible, so long-distance movement is essentially ichthyochory. Flowering falls in August and September as the rivers are sinking, maturation takes roughly nine months, and fruit abscission peaks from May to July at high water, with about four bunches per tree, each around 90 cm long and carrying some 106 fruits of 17 g. Pulp and seed consist mainly of water and carbohydrate, the seed carries 14.7% fat, the fruit is noted for an especially high vitamin A content, and the crop matters for floodplain fish nutrition. Habit is reported inconsistently: Palmweb's description opens with "solitary", while Kahn (2008) classifies the species as caespitose and other accounts describe clumps of four to six or more stems - so both solitary and clustering plants are evidently recognised. Where flooding has been altered the palm can take over. Downstream of the Balbina dam on the Uatuma River, Astrocaryum reached 98.40% relative density in intermediate topographies of the dammed reach, against 2.91% and 3.57% in the pristine Abacate and Jau areas. The species is assessed as Least Concern."

Use of the palm is long documented. Alfred Russel Wallace illustrated it as plate 42 of Palm Trees of the Amazon and Their Uses (1853), the source Kahn cites for the fruits being used as bait for fishing. Kahn (2008) lists the fleshy mesocarp as more or less sweet and edible, leaflet fibre worked into bags, hammocks and fishing nets, leaflets used for basketry, the endocarp made into rings, earrings and necklaces, and the rot-resistant stem used as building material; Palmweb adds house posts and thatch, and PACSOA notes the leaf stems used in basket weaving. Palm heart is eaten - Palmweb also records the plant taken medicinally against hepatitis - and Kahn notes attempts in Brazil to exploit A. jauari for palm heart canning in the Barcelos region, along with a 1990 proposal by Borgtoft Pedersen and Balslev to use the species in agroforestry systems. Kahn's fat figures are genus-wide rather than specific to this palm: about 20% in the mesocarp and 20-35% in the endosperm, the latter dominated by lauric acid, against the 14.7% measured in A. jauari seed by Piedade et al. Taxonomically the species sits in subgenus Astrocaryum, section Astrocaryum.