Here are the matches for the descriptions provided:
- Oats - a) Poaceae
- Onions - b) Liliaceae
- Stone fruit - e) Rosaceae
- Tobacco - f) Solanaceae
- Potatoes - f) Solanaceae
- Watermelons - d) Cucurbitaceae
Here is the complete list:
76. Oats - a) Poaceae
77. Onions - b) Liliaceae
78. Stone fruit - e) Rosaceae
79. Tobacco - f) Solanaceae
80. Potatoes - f) Solanaceae
81. Watermelons - d) Cucurbitaceae