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Volvox and Eudorina are two of the examples NCERT uses to teach how algae reproduce, and Chlamydomonas is on its list of common green algae. All three belong to a group of green algae called the Volvocales, and the person who spent his life studying that group in India was M. O. P. Iyengar of Madras. This post tells his story, explains his most famous discovery and links his work to the chapter you are studying.
Who was M. O. P. Iyengar?
An obituary in the Journal of the Marine Biological Association of India by R. Subrahmanyan gives the details. Mandayam Osuri Parthasarathy Iyengar was born in Madras on 15 December 1886. He studied at Presidency College, taking a BA in 1906 and an MA in 1909 with a thesis on algae. He worked as a curator at the Government Museum, Madras, from 1909 and taught at the Teachers' College from 1911.
In 1920 he became Professor of Botany at Presidency College, where he organised research on algae and freshwater life, probably the first to do so systematically in India. In 1930 he went to work with Professor F. E. Fritsch at Queen Mary College in London, earned a PhD from the University of London and was elected a Fellow of the Linnean Society. Back in India he took the newly created Chair of Botany at the University of Madras.
He was a foundation fellow of the Indian Academy of Sciences and of the National Institute of Sciences of India. He received the Birbal Sahni Gold Medal in 1957 and the Sunder Lal Hora Gold Medal in 1960. In 1959 he became the first President of the Phycological Society of India, and in 1963 the International Phycological Society elected him President. He was at his microscope until the morning of 6 December 1963, had a stroke that afternoon and died on 10 December.
Why did Madras suit an algae hunter?
T. V. Desikachary, his student, explains in a 2004 tribute in the Journal of Biosciences. Before Iyengar, knowledge of Indian algae depended on a few travellers whose base was outside India. Madras offered beach pools, agricultural fields and irrigation ponds that filled with the monsoon. In these temporary pools, Volvocales often grew almost alone, finished their life cycle in a few days and left so many zygotes that the sand turned brown. A couple of such cycles in a season gave him a steady supply of material, and he studied these pools all his working life.
What was Fritschiella?
In 1932 Iyengar described a new alga in Fritschiella, a new terrestrial member of the Chaetophoraceae in the New Phytologist, naming it after Fritsch. Desikachary describes it as heterotrichous: it has a part on the soil surface made of tissue-like filaments, upright branched filaments above, and colourless rhizoids that reach into the soil. He calls these features a parallel adaptation to life on land, similar to what land plants evolved, even though Fritschiella is not their ancestor. Twenty years later, Brook reported the same alga in Africa (1952), showing it was not confined to India.
Desikachary also describes Ecballocystopsis, an alga whose daughter cells stay held together by pieces of the old parent walls, forming a chain that looks like a filament without true connections. Iyengar used it to think about how single cells might have become many-celled.
How does his work connect to your NCERT chapter?
The NCERT Class 11 Plant Kingdom chapter classifies sexual reproduction in algae by the gametes:
Isogamous: gametes similar in size, flagellated as in Ulothrix or non-flagellated as in Spirogyra.
Anisogamous: gametes of different sizes, as in species of Eudorina.
Oogamous: a large non-motile female gamete and a small motile male gamete, as in Volvox and Fucus.
Eudorina and Volvox are colonial Volvocales, the group Desikachary says Iyengar's students studied in depth, including how colonies turn inside out during development. NCERT also lists green algae as having chlorophyll a and b, pyrenoids in the chloroplast and a cellulose wall.
Common mistakes:
Mixing anisogamy and oogamy. In oogamy the female gamete is non-motile. In anisogamy both may move but differ in size.
Calling Spirogyra anisogamous. NCERT lists it as isogamous with non-flagellated gametes.
Forgetting Fucus is a brown alga. It is NCERT's second oogamy example, but it is not a green alga.
Our plant kingdom guide for NEET covers the rest of the chapter, and our profile of Birbal Sahni, whose name is on one of Iyengar's medals, tells another story of Indian botany.
What can a student take from his way of working?
Study what is around you. He built a field from the pools of one city.
Wait for the full picture. Desikachary writes that he was reluctant to publish in a hurry and would wait to see a rare alga's whole life cycle.
Share your material. He gave collections and notes to students and visiting scientists.
Know the names first. He believed a good knowledge of an algal group's taxonomy comes before any research on it.
When the life cycles blur together
Algal life cycles are easier to keep apart when you can see each stage. The Fermi Concept Library has every concept in biology with its own lesson and its place in the map, so you can study one cycle at a time.
Try it now: without looking, list NCERT's three types of sexual reproduction in algae with one example each, then check against the chapter.
