Which gymnospermic plant is known for yielding an oil that is used to cure or relieve rheumatism?

Introduction / Context:
This question is from botany and medicinal plants. It focuses on gymnosperms, a group of seed producing plants that includes conifers and related species. Some gymnosperms have medicinal value. Here, the question asks which gymnospermic plant is associated with curing rheumatism, a painful condition affecting joints and connective tissues.

Given Data / Assumptions:
- The plant must be a gymnosperm. - It yields a product, particularly an oil, that is used against rheumatism. - The options are Ephedra, Pinus, Araucaria, and Gnetum.

Concept / Approach:
Gnetum is a genus of gymnosperms whose species produce an oil used traditionally to relieve rheumatic pain. Although other gymnosperms like Ephedra have medicinal properties, the specific match for rheumatism relief is Gnetum. This association is often highlighted in competitive exam oriented botany notes.

Step-by-Step Solution:
1. Recall that Ephedra is used mainly for respiratory disorders such as asthma. 2. Pinus species provide timber and turpentine but are not the primary textbook example for rheumatism relief. 3. Araucaria is widely ornamental and used as a timber source. 4. Gnetum species yield oils that are used in traditional medicine, especially against rheumatism. 5. Therefore, the gymnospermic plant that cures rheumatism is Gnetum.

Verification / Alternative check:
Botany reference books and question banks on gymnosperms explicitly mention Gnetum oil as being used for rheumatic pain. The same association is seen in many previous year questions.

Why Other Options Are Wrong:
Ephedra: Known mainly for containing ephedrine, used in respiratory and circulatory conditions. Pinus: Provides resin, turpentine, and timber; its primary noted use is not rheumatism cure in standard exam material. Araucaria: Primarily valued as an ornamental and timber tree, not highlighted for rheumatism treatment in common syllabi.

Common Pitfalls:
Students sometimes choose Ephedra because it is a well known medicinal gymnosperm. However, for rheumatism specifically, exams usually expect Gnetum. It helps to memorize a few key plant and disease pairings such as Gnetum and rheumatism for quick recall.

Final Answer:
The gymnospermic plant whose oil is used to cure rheumatism is Gnetum.