Introduction to the Non-Tracheophytes Classification Divided into 3 phyla Hepatophyta, liverworts Anthocerophyta, hornworts Bryophyta, mosses 9/21/2018

Characteristics of Non-Tracheophytes these are land plants with clearly visible alternation of generations. they are howe not well adapted to live on land; hence they need to be on moist and shady habitats. gametophyte generation is dominant, photosynthetic and nutritionally independent do not have the vascular tissue - hence Nontracheophytes or Non-Vascular plants 9/21/2018

Non-tracheophytes… they are low-growing plants because they do not have any strengthening and conducting tissue they have no roots, stems and leaves, but rhizoids, caulidia and phyllidia respectively. free water is essential for sexual reproduction the male gamete swims to the female gamete by chemotaxis, so sexual reproduction can only occur in wet conditions 9/21/2018

Non-tracheophytes… gametes are produced in sex organs called: antheridia - produce sperms archegonia - produce eggs (ova) sexual reproduction is oogamous, i.e., only the male gamete is mobile and fertilisation takes place in the archegonium 9/21/2018

Non-tracheophytes sporophyte comprises a foot, stalk (seta) and capsule (sporangium) may or may not be photosynthetic but is nutritionally dependent on the gametophyte and permanently attached to it spores are borne in a capsule and are produced by meiosis, hence haploid dry conditions are necessary for spore dispersal 9/21/2018

Nontracheophytes… they carry out asexual reproduction by: Fragmentation the production of minute bodies called gemmae, which give rise to new plants 9/21/2018

Characteristic features used to distinguish between the different phyla of Non-Tracheophytes Differences in the three Non-tracheophyte phyla are based on: the nature of the plant body, whether it is: Thalloid - a multicellular body not differentiated into stems, root and leaves OR Leafy - whether the plant has caulidia, phyllidia and rhizoids, and thus resembling a true plant. the nature of the phyllidia (if present) development of the juvenile phase of the gametophyte (protonema) the presence or absence of an opening mechanism in the capsule 9/21/2018

1. Phylum Hepatophyta (Liverworts) called liverworts because they were thought to resemble the liver and the believe that they could cure any liver ailments. This is thought to be the most primitive of the Non-tracheophytes Gametophyte: maybe thalloid or “leafy”. 9/21/2018

Phylum Hepatophyta… germinating spores either develop directly into the gametophyte with no protonema or with a very reduced protonema rhizoids are unicellular Sexual reproduction: the sex organs are either found embedded on the upper surface of the thallus, or on special branches, archegoniophores and antheridiophores. 9/21/2018

Hepatophyta… in Marchantia polymorpha, gametophytes either male or female, i.e., the species is dioecious. in Riccia, male sex organs antheridia and archegonia are embedded on the same gametophyte, i.e., it is monoecious. 9/21/2018

Liverworts… Sporophyte Simple, made up of foot, seta and capsule (sporangium) Haploid spores produced in the capsule by meiosis Other cells called elaters also present in the capsule Spore Dispersal: dehiscence of capsule is by elaters 9/21/2018

Phylum Anthocerophyta (Hornworts) formerly included with the Hepatophyta because of their thalloid nature now placed in a separate phylum, mainly on the account of their unique sporophyte. Gametophyte the hornworts have the simplest gametophyte of the Nontracheophytes. they are always thalloid, with numerous unicellular rhizoids growing from the lower surface. 9/21/2018

Anthocerophyta… there is a single large chloroplast per cell in the thallus. there is no protonemal stage. Sexual Reproduction: the sex organs are embedded in the upper layer of the thallus numerous antheridia in a single antheridial chamber. antheridia similar in structure to the Hepatophyta 9/21/2018

Anthocerophyta… the archegonia are embedded within the thallus. Have unique sporophyte the capsule is needle-shaped (or cylindrical) rather than spherical like those of other Non tracheophytes. when ripe the capsules split from the tip downward into two halves. 9/21/2018

Phylum Bryophyta (Mosses) Gametophyte: germinating spores of mosses do not develop directly into leafy gametophyte but go through the protonemal stage. The protonema is anchored by rhizoids to the substrate rhizoids are multicellular gametophytes are “leafy”, never thalloid the “leaves” are spirally arranged on the caulidia 9/21/2018

Bryophyta Sexual Reproduction: gametophytes of many mosses are monoecious (homothallic), i.e., both antheridia and archegonia are produced on the same gametophyte. some mosses are dioecious (heterothallic), i.e., antheridia and archegonia are produced on separate gametophytes antheridia and archegonia develop at the apex of the leafy gametophyte 9/21/2018

Mosses… the sex organs occur in clusters referred to as: an archegonial head or an antheridial head the sex organs are separated by structures called paraphysis (ses) the antheridial head are in turn enclosed by special leaves called perigonia similarly the archegonial head is enclosed in perichetia only one archegonium is fertilised per head. 9/21/2018

Mosses… Sporophyte Made up of a foot, a seta and a capsule Capsule often covered by operculum Capsule may be photosynthetic Spores produced by meiosis 9/21/2018

Mosses… Spore Dispersal: capsule of sporophyte has an elaborate mechanism of spore dispersal, dependent on dry conditions and involves the use of peristome teeth Basic mechanism with some variations The operculum, (which covers the capsule) falls off, to expose peristome teeth which surround the mouth of capsule Peristome teeth open Spores released and dispersed by wind 9/21/2018

Life cycle Generalised life cycle of non-Tracheophytes. 9/21/2018