spirally around the crown of the trunk. The 40–130 cm long petiole of the leaf has margins armed in stiff teeth which may grow up to 4 cm in length, as well as fibres along the margins. The leaf has a rachis that is 163–200 cm in length. There are (57-)63-78 glaucous-coloured pinnae (leaflets) along this rachis, these pinnae are (58-)65–77 cm long and 2–3 cm wide in the middle of the leaf. The pinnae are inserted at a single plane on both sides of the rachis, such that each pair of pinnae form a 'V'-shape. Inflorescence The developing inflorescence is protected within a woody, hairless spathe which is lightly striated and 105–135 cm in total length, the swollen part of this spathe being 40–110 cm long and 7–14 cm wide. The branched inflorescence has a 40–75 cm long and 1.5-2.2 cm wide peduncle (stalk). The rachis of the inflorescence is 40–72 cm long and has 68-155 rachillae (branches) which are 16–72 cm long. The flowers are coloured yellow, yellow-purple, greenish-yellow or entirely purple. The staminate (male) flowers are 9-10mm in length; the pistillate (female) flowers 13–17(–18)mm. Compared with other extant palms in the region, Butia yatay has the largest-sized pollen grains on average. They are bilaterally symmetrical, suboblate-shaped, the end piriform (pear-shaped), and monosulcate. The surface is covered in minute 2μm-large reticulate patterns. Fruit & seeds The shape of the fruit is ovoid. The shape of the 1.8-2.8 by 1-1.7 cm nut is elongated, ellipsoid or turbinate, and it weighs 1.1-3.5g. The ripe fruit are by in size, weigh , and have a persistent perianth. The fruit may be coloured yellow, orange, red, or purple, while the flesh is yellow, sweet, juicy, and slightly fibrous. The nut often has a beak or protuberance at its extremities, and has homogeneous endosperm and from 1 to 3 seeds. Similar species In his 1979 key to the genus Butia, Glassman compares this species with B. paraguayensis, the main differences being the taller trunk, the longer leaf rachis with more wider and longer pinnae, the spathe (being almost twice the size), and larger fruit, beyond the range of B. paraguayensis. Distribution In Brazil it only occurs in the southernmost state of Rio Grande do Sul, and there only in the municipalities of Giruá and Quaraí. In Argentina it occurs in the northern-center provinces of Chaco, Corrientes, Entre Ríos, Misiones (in the municipalities of