Definition/Characteristics of the Hepaticeae (Liverworts)

Over 1M Answers AvailableCategory: BiologyDefinition/Characteristics of the Hepaticeae (Liverworts)
Gen. Sulhazan Staff asked 3 months ago

state the characteristics/features of liverworts

1 Answers
Mark Moon answered 3 months ago

There is great diversity in external form among gametophytes of the various genera of the Hepaticae, but all of them are fundamentally alike in that they are dorsi ventrally differentiated and develop sex organs terminally or from superficial cells on the dorsal side of the thallus. The sporophytes are all alike in that they are strictly limited in growth and wholly parasitic upon the gametophyte. The class includes some 8,500 species grouped in about 175 genera.
The Hepaticae are less advanced than are other Bryophyta, but the decision as to which is the most primitive order of the class depends upon
the criteria established. From the standpoint of gametophytic structure, Sphaerocarpo8 is the simplest of living liverworts. From the standpoint of sporophytic structure, the Ricciaceae are the simplest. Since the great phylogenetic sweep from Bryophyta upward is in the evolution of the sporophyte, the liverworts with the simplest sporophytes, the Ric￾ciaceae, are best placed first among the Hepaticae, even though they belong to an order which shows the greatest internal differentiation of any gametophyte.
Until the beginning of the present century, the families here placed in the Hepaticae were segregated into two ord.ers (Marchantiales and
Jungermanniales). Recent investigations show that Sphaerocarpo8 and  its immediate relatives should be placed in a separate order. The Calo￾bryaceae merit the same consideration. Acceptance of these proposals results in a segregation of the Hepaticae into four orders.