In flowering plants, which structure serves as a nutritive tissue that supports and nourishes the developing embryo inside the seed?

Introduction / Context:
This botany question focuses on seed development and the tissues that nourish the embryo in angiosperms. After fertilisation, specific tissues form to provide food for the growing embryo. Understanding which structure is specialised as nutritive tissue is important for plant physiology, agriculture, and exam questions related to double fertilisation.

Given Data / Assumptions:
- The options list ovule, zygote, ovary, and endosperm. - The question asks which serves as nutritive tissue for the growing embryo. - Standard angiosperm fertilisation and seed formation processes are assumed.

Concept / Approach:
In flowering plants, double fertilisation occurs. One male gamete fuses with the egg cell to form the zygote, which develops into the embryo. The other male gamete fuses with the two polar nuclei in the central cell of the embryo sac to form primary endosperm nucleus, which develops into endosperm. Endosperm is a triploid tissue in many plants and acts as a nutritive tissue, storing starch, oils, and proteins to support the embryo. The ovule becomes the seed, and the ovary becomes the fruit, but the key nutritive tissue is the endosperm.

Step-by-Step Solution:
Step 1: Recall that fertilisation in angiosperms produces two main products, the zygote and the primary endosperm nucleus. Step 2: Recognise that the zygote undergoes divisions to form the embryo, which will develop into the new plant. Step 3: Understand that endosperm forms from the fusion of a male gamete with the two polar nuclei and grows as a nutritive tissue. Step 4: Observe that the ovule as a whole develops into the seed, containing embryo and nutritive tissues, but is not itself the nutritive tissue. Step 5: Note that the ovary develops into the fruit wall and does not feed the embryo directly. Step 6: Conclude that endosperm is the tissue whose main role is nourishment of the developing embryo.

Verification / Alternative check:
To verify, think about common food grains like wheat, rice, and maize. The part we eat is mostly endosperm, rich in stored nutrients. Textbooks often mention that cereals have endospermic seeds where endosperm persists and nourishes the embryo during germination. Non endospermic seeds use cotyledons as food storage, but even then, the origin of nutritive material is linked with endosperm formation. This strong association between endosperm and nutrition confirms it as the correct answer.

Why Other Options Are Wrong:
Ovule: The ovule is the entire structure that becomes the seed after fertilisation and includes integuments, embryo sac, and later embryo and endosperm, but it is not specifically the nutritive tissue. Zygote: The zygote develops into the embryo and is the future plant, not the tissue that nourishes the embryo. Ovary: The ovary is the part of the carpel that encloses ovules and later forms the fruit wall, which plays a protective and dispersal role rather than directly feeding the embryo.

Common Pitfalls:
A common mistake is to confuse the entire seed or ovule with the nutritive tissue inside it. Another pitfall is to think of the zygote as the source of nutrition simply because it is central to development. Remember that nutrition requires stored food, and in many angiosperms the specialised storage tissue is the endosperm. Associating endosperm with the nutrient rich part of grains is a helpful memory aid.

Final Answer:
The structure that serves as nutritive tissue for the growing embryo is the Endosperm.