Step 1: Understanding the Concept:
Weed seeds employ diverse dispersal modes (called "chories") utilizing physical agents (wind, water) or biological vectors (animals, insects) to colonize new areas.
Step 3: Detailed Explanation:
Let us define the listed terms:
1. Myrmecochory: The dispersal of seeds specifically by ants.
Many weed seeds have oily attachments called elaiosomes that attract ants, which carry the seeds to their nests, assisting in seed distribution and underground planting.
2. Autochory: Self-dispersal or mechanical explosive release of seeds by the plant itself (e.g., Impatiens).
3. Blastochory: Dispersal of seeds where the stem of the plant crawls along the ground to deposit seeds.
4. Herpochory: Dispersal of seeds by creeping or crawling motions of the seed appendages (like awns) in response to humidity changes.
Therefore, seed dispersal by ants is Myrmecochory.
Step 4: Final Answer:
The correct option is 1, which corresponds to Myrmecochory.