Ans. In protostele xylem surrounds phloem.
The type includes Haplostele, Actinostele, Plectostele and mixed protostele.
(i) Haplostele: Xylem surrounded by phloem is known as haplostele. e.g., Selaginella.
(ii) Actinostele: Star shaped xylem core is surrounded by phloem is known as actinostele. e.g., Lycopodium serratum.
(iii) Plectostele: Xylem plates alternates with phloem plates. e.g., Lycopodium clavatum.
(iv) Mixed prototostele: Xylem groups uniformly scattered in the phloem. e.g., Lycopodium cernuum.

1. Rhodophyceae commonly called as red algae.
2. Mostly marine habitats.
3. The thallus is multicellular, macroscopic, and may be filamentous, ribbon-like etc.
4. Chlorophyll 'a', r-phycoerythrin and r-phycocyanin are photosynthetic pigments.
5. Asexual reproduction is by means of monos pores, neutral spores and tetraspores.
6. Floridean starch is the storage material
7. Sexual reproduction in oogamous.
8. Male sex organ is spermatangium producing spermatium.
9. Female sex organ is carpogonium.
10. Spermatium is carried by water and fuses with egg forming zygote.
11. Zygote undergoes meiosis forming carpospores.
12. Alternation of generation is seen. Example: Ceramium, Gelidium and Gigartina.

Gymnosperms resemble angiosperms in the following features:
1. Presence of well organised plant body which is differentiated into roots, stem and leaves.
2. Presence of cambium in gymnosperms as in dicotyledons.
3. Flowers in Gnetum resemble the angiosperm male flower. The Zygote represent the first cell of sporophyte.
4. Presence of integument around the ovule.
5. Both plant groups produce seeds.
6. Pollen tube helps in the transfer of male nucleus in both.
7. Presence of Eustele.

1. Members of this group include 'Red algae' and are mostly marine. The thallus is multicellular, macroscopic and diverse in form.
 2. Porphyridium is the unicellular form. Filamentous (Goniotrichum) ribbon like (Porphyra), Corallina and Lithothamnion are heavily impregnated with lime and form coral reefs.
3. Apart from chlorophyll a r-phycoerythrin and r-phycocyanin are the photosynthetic pigments.
4. Asexual reproduction takes place by means of monospores, neutral spores and tetraspores. The storage product is floridean starch.
5. Sexual reproduction is oogamous. Male sex organ is spermatangium which produces spermatium. Female sex organ is called carpogonium.
6. The spermatium is carried by the water currents and fuse with egg nucleus to form zygote.
7. The zygote develops into carpospores. Meiosis occurs during carpospore formation.
8. Alternation of generation is present. Eg: Ceramium, Polysiphonia, Gelidium, Cryptonemia and Gigartina.