22 1 
A nacrogynous Jlingermanniales. 
sided apical cell and consisting of a cylindrical stem and spirally 
arranged leaves. Muller (52) in his description of Haplomitrium, 
states that the leaves are irregularly disposed on the stem, but 
Stephani (66) states that in both genera there is a distinction 
between two rows of obliquely inserted leaves, and a third row 
of transversely inserted leaves, the latter corresponding to the 
ventral leaves or amphigastria of the Acrogynae. Goebel (21) 
describes the same arrangement in Calobvyum Blumei, where the 
transversely inserted row, consists of leaves only half as large as 
those in the other two rows. 
In Haplomitrium the shortly-stalked ovoid antheridia are borne, 
usually in groups of two or three, in the axils of the upper leaves 
of the male plant; according to Stephani they are never found in 
the axils of the transversely inserted leaves (amphigastria), but 
Muller (52) says that they are arranged all round the stem and may 
also occur on the stem surface without any relation to the leaves. 
Gottsche in his classical memoir (27) gives the same account 
as Muller. The archegonia are also developed in the axils of the 
uppermost leaves of the female plant, these leaves being usually 
larger than the others; there is no involucre or perianth, but the 
sporogonium is protected by a large cylindrical calyptra. The 
development of archegonia does not arrest the apical growth of the 
shoot; the apical cell is not used up in the formation of an arche- 
gonium, and sometimes the apical growth of the shoot is resumed 
after the formation of a sporogonium. The oblong capsule usually 
opens by two or three valves ; the wall consists of a single layer 
of cubical cells, each having a single thickened ring-like band 
extending over the horizontal and tangential walls of the cell, 
instead of being set transversely to the long axis of the capsule as 
are the ring fibres in the capsule-wall of other Hepaticae. 
In Calobryum, which has the same general habit as Haplo¬ 
mitrium, the leaves are apparently arranged more definitely in three 
rows, and both the antheridia and the archegonia are developed in 
groups on the flattened and broadened apex of the stem. In both 
cases the group of sexual organs is surrounded by three large 
spreading leaves, so that the plant has a close superficial 
resemblance to the male “flower” of Funaria or Mnium. In the 
development of the archegonia, the apical growth of the plant is 
arrested, hence Calobryum is definitely acrogynous. The sexual 
organs, calyptra, and sporogonium have the same structure as in 
Haplomitrium. 
