It is characterized by verticils with relatively long, spatulate, mucronate leaves.
Most comparable to Annularia mucronata are the specimens described by Elias (1931) as Carpannularia, a genus based on the presence of some reproductive structures (which Elias assumed to be seeds) that are attached to Annularia-type verticils. Abbott (1958) accepted the connection between these "seeds" and the leaf verticils and synonymized Elias's Carpannularia americana with Annularia stellata.
DESCRIPTION: Ultimate axes longitudinally striate, 0.8-1 mm wide, with internodes 10-12 mm apart, bearing verticils that touch or slightly overlap when spread out on the bedding plane.
Annularia jongmansii is characterized by anisophyllous verticils with lanceolate leaves showing a subrounded apex that includes a tiny mucron.
In addition, leaves of Annularia galioides are of near-equal length in almost isophyllous verticils. Annularia microphylla has verticils with lanceolate and sickle-shaped leaves of equal length and stiffer aspect.
Verticils of Annularia fertilis have isophyllous leaf whorls, with oblong, longer leaves, with a greater length/breadth ratio.
0.75 mm wide, with internodes 4.5-5 mm long bearing verticils that touch or slightly overlap.
DESCRIPTION: Ultimate axes longitudinally striate, 1-2 mm wide, with internodes 9-14 mm apart bearing verticils flattened in the same plane as the axis, each with 10-14 leaves that overlap slightly.
4 (= Annularia sp., anisophyllous verticils with leaves showing a more acute apex than in Annularia radiata).
1-1.5 mm wide, with internodes 10-25 mm apart bearing verticils spread out on the bedding plane that touch but do not overlap.
She also noted that Annularia acicularis has anisophyllous leaf verticils, in contrast to the isophyllous verticils of Annularia radiata.
COMPARISONS: Annularia fertilis possesses isophyllous verticils with a similar number of leaves to that in Annularia radiata; however, these are oblong, with an acute, mucronate apex.