Coccothrinax readii is a small, solitary palm 1-4 m high, with a very slender, brownish or grayish trunk 3-5 (-5.5) cm in diam. bearing a small open crown of 9-16 palmate leaves. Leaf blades are 40-110 cm in diam., dark green above and silvery on the abaxial surface, with 39-54 segments connate in a palman 13-30 cm long, the free portion triangular, generally tapering to a bifid apex to 3 cm deep, sometimes abruptly constricted in the middle of the free portion, middle segments 40-65 (-71) cm long from hastula to apex, the widest point always over the sinus, 2-3.8 cm wide; petioles 25-110 cm long, 6-11 mm wide at the most slender point and 815 mm wide at the union with the sheath, biconvex to narrowly rhombic in cross section and flattened adaxially toward the base; sheath linguiform, free portion 3-6.8 (-9.5) cm long from the union with the petiole, woven of fine fibers and forming a looser net with age; hastula narrowly triangular, sometimes only slightly retuse apically, but mostly very deeply bifid to 7.5 mm, free portion 9-25 mm long, sometimes tubular; abaxial hastula 1.7-4 mm long. Inflorescence interfoliar, arcuate in fruit, (37-) 40-84 cm long, bearing 4-7 (-9), usually 5, primary branches, the lowermost branch 9-25 cm long with 6-20 (-25) rachillae (3-) 4.5-11 cm long. Flowers fragrant, creamy-white; perianth in a single series with (4-) 5-6 unequal, subulate lobes; stamens (8-) 9-11 (-13) longer than pistil, filaments connate at the base in a ring around the base of the ovary, anthers retuse to bifid at the apex, sagittate at the base, longer than filaments, thecae unequal 2-3.7 mm long; pedicels 1.5-4 mm long. Fruit subglobose, purple-black and juicyfleshed at maturity, 5-12.5 mm in diam. with persistent perianth and filaments; fruiting pedicels 2-6.5 mm long; seed brownish, subglobose, cerebriform, 3.5-10 mm in diam.
Truncus simplex, caule gracili usque ad 4 m alto, plerumque minus quam 5 em lato; folia palmata ambitu orbicularia, pagina supra atroviridi infra argentea et non punctulata, lamina in 39-54 segmenta divisa, segmentis centralibus usque ad 65 em longis apice bifurcatis, ad 3.8 cm latis supra sinus, hastula apiculata bifida 0.9-2.5 cm longa, vagina linguiformi, parte libera usque ad 6.8 cm longa; in florescentie non elongatae 4-7 (-9)-partitae plerumque 5, floribus eburneis, fragrantibus, pedicellis 1.5-4 mm longis, perianthio 5-6-partito, segmentis subulatis, staminibus 9-13, antheris 2-3.7 mm longis, basi in forma sagittis; inflorescentiae fructificantes arcuatae, fructibus subglobosis purpureo-nigris, 5-12.5 mm diam., pedicellis fructiferis 2-6.5 mm longis, semine 3.5-10 mm diam.
Coccothrinax readii is a very abundant palm where it grows, occurring in Median or Low Tropical Rain Forests near the coast and in Sandy Coastal Dunes. In the Median Forest, this palm is an important element of the physiognomy. It is very abundant in the median stratum under the shade of species such as Manilkara zapota, Metopium brownei, Caesalpinia gaumeri, etc. It grows under conditions of high humidity and on shallow soils with abundant humus not more than 10 to 15 cm deep where it reaches its best development. It is common to find it with brownish trunks usually tall (4 m), but very slender, not more than 4 cm in diameter. Leaves are large, 80-110 cm in diameter, with petioles 70-110 cm long. The hastula can be slightly bifid and is frequently tubular on account of the expansion of the blade. This kind of forest with knacas is exclusively found in Quintana Roo, from the south to the environs of Cancun: it is in the southern region that C. readii grows farthest inland (30 km), while it is never found more than 2 km inland in the environs of Cancun. The Low Forest where this palm is found is in the transition zone between the Median Forest and the Sandy Dunes. These forests grow in the middle region of Quintana Roo (environs of Tulum) near the coast where the humidity is also high but soils are poorer and very rocky, with coralline limestone outcrops. The habit of C. readii is similar to that of specimens of Median Forest, but it is generally smaller, the mean height being 2.5 m. The palm is associated with Metopium brownei, Thevetia thevetioides, Acacia gaumeri, Pithecellobium platylobum, Beaucarnea pliabilis, and Pseudophoenix sargentii. This species grows on Sandy Dunes from the coast of Tulum in Quintana Roo to Sisal in Yucatan, where it is exposed to the sun and sea breezes, and it is here that C. readii presents its widest variations. It is generally smaller, but trunks are wider and grayish, the hastula is deeply bifid, the inflorescences are shorter and frequently the terminal primary branches are not well developed. In the dunes of Tulum, humidity is high: this zone is exposed to frequent rainfall, as well as to the strong sea breezes. Here, C. readii is very vigorous, more than 2 m high with trunks 5 cm in diameter, and leaves are large, to no cm in diameter, with segments to 3.8 cm wide and petioles 1 m long. Other species growing in these dunes are Thrinax radiata, Chrysobalanus icaco, Metopium brownei, Coccoloba uvifera, Cordia sp., etc. In the dunes of Punta Sam, this palm grows 2 m high, although it is generally smaller, the width of trunks reaches 5.5 cm, the leaves are smaller- 40-70 cm in diameter, petioles 25-50 cm long, hastula to 2.5 cm long and deeply bifid (to 7 mm}-and the inflorescence is 30-50 cm long. Associates are Pithecellobium keyense Chrysobalanus icaco, Sophora tomentosa, Coccoloba uvifera, and Thrinax radiata. The region of EI Cuyo on the northern coast of Yucatan limits a coastal lagoon, therefore the humidity is high. Coccothrinax readii is found here growing 2 m high, the leaves are larger than those of Punta Sam, to 90 cm in diameter, the petioles are to 60 cm long, and the inflorescences to 50 cm long. Other associated species are Pseudophoenix sargentii, Thrinax radiata, Metopium brownei, Agave sp., and several species of cactus. The environs of Chelem, on the northwestern coast of Yucatan, near Sisal, are one of the driest regions of the Peninsula and they are the limit of distribution of the species. This palm is there represented by depauperate individuals 1-1.5 m high, with slender trunks to 4 cm in diameter, leaves 4050 cm diameter, petioles to 40 cm long. The inflorescences are very short and the branches are not well developed. The species grows with Thrinax radiata, Metopium brownei, Gossypium hirsutum, Malvaviscus arboreus, and different kinds of cactus. There are three islands near the northeastern coast of the Peninsula: Cozumel, Isla Mujeres, and Contoy. It is interesting to emphasize that scattered individuals of this species are found only in Cozumel, none on the other islands.