Q.48 Which of the following is the closest ancestor of all land plants?
(A) Blue green algae
(B) Red algae
(C) Chara
(D) Coleochaeteae

The correct answer is: (D) Coleochaeteae.
In classical botany MCQs, Coleochaete and its allies (Coleochaeteae) are usually considered the closest algal relatives and thus the closest ancestor-like group to land plants.​

Correct Answer Explained: Coleochaeteae

In most standard botany texts and entrance-exam style questions, members of Coleochaeteae (especially the genus Coleochaete) are described as the closest algal relatives of land plants. These green algae share several key traits with land plants, including:​

• Presence of chlorophyll a and b and storage of starch inside chloroplasts, like land plants.​

• Protective covering (sporopollenin-like wall) around zygotes/spores, considered a crucial adaptation that parallels early land plant reproductive structures.​

Because of these shared characters and their position within the charophyte green algae lineage, Coleochaete and related forms are traditionally cited as the closest ancestor or closest living relatives of land plants in many academic questions.​

Why the Other Options Are Incorrect

(A) Blue green algae

• Blue green algae are cyanobacteria, which are prokaryotic organisms, not true algae or plants.​

• They contributed historically to oxygenation of Earth and to the origin of chloroplasts via endosymbiosis, but they are far more distantly related to land plants than green algal groups like Coleochaeteae.​

So, cyanobacteria are important in evolutionary history but are not the closest ancestor of land plants.

(B) Red algae

• Red algae (Rhodophyta) are eukaryotic algae with phycobilin pigments and lack flagellated stages, differing strongly from land plants.​

• Molecular and morphological data place them on a separate branch from the green plant lineage (Viridiplantae), which includes green algae and land plants.​

Therefore, red algae are not considered the nearest ancestors of land plants.

(C) Chara

• Chara belongs to the order Charales, a group of charophyte green algae that are indeed very closely related to land plants and historically were often treated as the closest relatives.​

• However, many modern treatments and exam patterns distinguish Coleochaete (Coleochaeteae) as an even closer or more representative model of the immediate algal relatives of land plants, especially due to zygote protection and developmental similarities.​

So Chara is very close but not the best answer when Coleochaeteae is specifically given as another option.

(D) Coleochaeteae – The Best Answer

• Coleochaeteae are small, freshwater green algae placed within charophyte green algae, the group from which land plants arose.​

• Features like retention and protection of the zygote on the parental thallus and sporopollenin-like walls around spores make them an excellent modern analogue of the earliest land plant ancestors, which is why they are singled out in exam questions as the closest ancestor of all land plants.​

Hence, among the given options, Coleochaeteae (D) is the correct and most accepted answer.