Tag: plant kingdom

Mosses show an advance on some liverworts in that the plant body is differentiated into simple stems and leaves, though it has no roots, rhizoids still being present, but these are multicellular and have oblique septa.
Liverworts and hornworts have dorsiventrally flattened lobed plant body, with unicellular rhizoids.

• A protonema is a thread-like chain of cells that forms the earliest stage (the haploid phase) of a bryophyte (e.g., Funaria) life cycle. When a moss first grows from the spore, it grows as a protonema which develops into a leafy gametophore. 
• Moss spores germinate to form an alga-like filamentous structure called the protonema. It represents juvenile gametophyte. While the protonema is growing by apical cell division, at some stage, under the influence of the phytohormone cytokinin, buds are induced which grow by three-faced apical cells. 
• These give rise to gametophores, stems and leaf-like structures (bryophytes do not have true leaves (megaphyll). These gametophores are the adult form of the gametophyte. 
• Protonema are characteristic of all mosses and some liverworts but is absent from hornworts. The protonema is also the photosynthetic part of a germinating fern spore.

Liverworts are small green flowerless plants with lobed leaves. These lack true roots. They reproduce by means of small cup-shaped structures called the gemmea and by fragmentation of thalli.

Funaria (bryophyte), Dryopteris (pteridophyte), and Ginkgo (gymnosperm) all produce archegonia as their female reproductive organ. They differ significantly in vascular tissue and the independence of their sporophyte/gametophyte generations.

Funaria is an acrocarpous moss, meaning the sporophyte develops at the apex of the main gametophyte shoot. This is a characteristic feature of the genus.

androcyte mother cells are formed from the division and re-division of the primary androgonial cell. Each androcyte mother cell divides to form two andro­cytes. The androcytes transform into biflagellate antherozoids or sperms.

In mosses, fertilization occurs within the archegonium, where the egg cell is located. The resulting zygote develops directly into the sporophyte while attached to and dependent on the gametophyte at the archegonium.

An immature male gametophyte (pollen grain) consists of a vegetative cell and a generative cell. Upon pollination and germination, the generative cell divides mitotically to produce two male gametes, forming the mature male gametophyte.

The sex organs in bryophytes (Riccia, Funaria), are multicellular and jacketed. The jacket of the sterile cell around the sperm and egg is an adaptation to a life on land. The male reproductive organs are antheridia and female reproductive organs are archegonia.

The sex organs in bryophytes {Riccia, Funaria), are multicellular and jacketed. The jacket of the sterile cell around the sperm and egg is an adaptation to a life on land. The male reproductive organs are antheridia and female reproductive organs are archegonia.