Crossword clues for marchantiales
marchantiales
The Collaborative International Dictionary
Marchantiales \Marchantiales\ prop. n. An oder of liverworts with gametophyte differentiated internally.
Syn: order Marchantiales.
Wikipedia
Marchantiales is an order of thallose liverworts that includes species like Marchantia polymorpha, a widespread plant often found beside rivers, and Lunularia cruciata, a common and often troublesome weed in moist, temperate gardens and greenhouses.
As in other bryophytes, the gametophyte generation is dominant, with the sporophyte existing as a short-lived part of the life cycle, dependent upon the gametophyte.
The genus Marchantia is often used to typify the order, although there are also many species of Asterella and species of the genus Riccia are more numerous. The majority of genera are characterized by the presence of (a) special stalked vertical branches called archegoniophores or carocephala, and (b) sterile cells celled elaters inside the sporangium.
Usage examples of "marchantiales".
The lower members of the Jungermanniales are also thalloid, but the thallus never has the complicated structure characteristic of the Marchantiales, and progress is in the direction of the differentiation of the plant into stem and leaf.
The Marchantiales form an obviously natural evolutionary group, and the same is probably true of the Jungermanniales, although in neither case can the partial lines of progression within the main groups be said to be quite clear.
The Marchantiales are a series of thalloid forms, in which the structure of the thallus is specialized to enable them to live in more exposed situations.
In the Marchantiales the chief supply is obtained from the soil by the rhizoids, and its loss in transpiration is regulated and controlled.
Sometimes adaptations to protect the plant during seasons of drought, such as the rolling up of the thallus in many xerophytic Marchantiales, can be recognized, but more often a prolonged dry season is survived in some resting state.
The Marchantiales are divided into a number of groups which represent distinct lines of advance from forms like the Ricciaceae, but the details of their classification cannot be entered upon here.