Pharmaceutical botany - Lighthouse Survival Blog

MUSCI OR MOSSES 65
Order i. Marchantiales, including Marchantia and Riccia.
Order 2. Jungennaniales, the leafy liverworts, including Porella.
Order 3. Anthocerotales, having the most complex sporophyte gen-
erations among liverworts, including Anthoceros, and Megaceros.
SUBDIVISION II.—MUSCI OR MOSSES
Plants found on the ground, on rocks, trees and in running water.
Their life histories consist of two generations, gametophyte and sporophyte
similar to the liverworts but differ from liverworts, generally, by
the ever-present differentiation of the gametophyte body into distinct
stem and simple leaves, and the formation of the sexual organs at the
end of an axis of a shoot. They are either monoecious, when both kinds
of sexual organs are borne on the same plant, or dioecious, in which case
the antheridia and archegonia arise on different plants.
Order i. Sphagnales, or Bog Mosses, including the simple genus.
Sphagnum. Pale mosses of swampy habit whose upper extremities re-
peat their growth periodically while their lower portions die away grad-
ually and form peat, hence their frequent name of Peat Mosses.
Order 2. Andreaeales, including the single genus Andreasa, a xero-
phytic habit occurring on siliceous rock.
Order 3. Bryales, or true mosses comprising the most highly evolved
type of bryophytes. Ex. : Polytrichum, Funaria, Hypnum, and Minium.
Life History of Polytrichum Commune (a Typical True Moss)
Polytrichum commune is quite common in woods, forming a carpet-like covering
on the ground beneath taU tree canopies. It is dioecious, the plants being of two
kinds, male and female.
Begiiming with a spore which has fallen to the damp soil, we note its beginning
of growth (germination) as a green filamentous body called a protonema. This
protonema soon becomes branched, giving rise to hair-like outgrowths from its
lower portion called rhizoids and lateral buds above these which grow into leafy
stems commonly known as " moss plants." At the tips of some of these leafy stems
antheridia (male sexual organs) are formed while on others archegonia (female
sexual organs) are formed. These organs are surrounded at the tips by delicate
hairy processes called paraphyses as well as leaves for protection. The antheridia
bear the antherozoids, the archegonia, the eggs or ova, as in the Uverworts. When
an abundance of moisture is present the antherozoids are liberated from the anther-
idia, swim through the water to an archegonium and descend the neck canal, one
fertilizing the egg by uniting with it. This completes the sexual or gametophyte
generation. The fertilized egg now undergoes division until an elongated stalk
bearing upon its summit a capsule is finally produced, this being known as the sporo-
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