Cypselae oblong to sub-obovate, truncate, attenuate to
rostrate at the apex, glabrous to pubescent, sometimes dimorphic with the marginal cypselae conspicuously larger than the central ones; pappus of scabrid to plumose bristles, capillary to narrowly paleaceous, often plumose only at the apex, equal to different in length, less commonly reduced to a crown of fringed scales, or pappus absent.
However, the conical shape of the operculum appeared to be a synapomorphy of the clade A, depicting secondarily
rostrate shape in isolated taxa.
Capsule green, fusiform,
rostrate, 5.3-6 cm long, ca.
Glabrous anthers, obcordate, dorsifixed (versatile), 0.3-0.5 cm long; slightly
rostrate connective; filament glabrous or slightly pilose at the base, usually narrowing towards the anther, 0.6-0.8 cm long.
Bas.: Synedra lanceolata Kutzing Valves linear, sometimes narrowed at valve center, with
rostrate or subcapitate ends.
Silveira, but the latter species differs in the fleshy and grooved annulus, the shape of pleuroclirysocystidia and cheiloclirysocystidia, which are broadly fusoid and bear a
rostrate apex, and the presence of cheiloleptocystidia and pileipellis strongly gelatinized; in addition, it is a more robust mushroom (Cortez & Silveira, 2008).
Cypselae
rostrate at the apex, pubescent; pappus of scabrid, capillary bristles.
Hexopetion and Astrocaryum are superficially similar in sharing the white indument on abaxial surface of pinnae, flattened spines, robust inflorescence branched to one order with catkin-like staminate rachillae or distal portion of them, pistillate flower(s) basal and considerably larger than staminate ones, fruits large, oval-obovoid,
rostrate, spiny, endocarp with superficial black fibers forming a star-like pattern around germinating pores.
Cypselae
rostrate to slightly constricted at the apex, pubescent; pappus of scabrid, capillary bristles.
Cypselae dimorphic; marginal cypselae rudimentary,
rostrate at the apex, glabrous or pubescent; central cypselae ribbed, very hairy at the base or pubescent throughout; pappus of numerous, persistent scales.
