The largest and heaviest seed is that of
Lodoicea
The largest seed in the world is the coco de mer (Lodoicea maldivic), the seed of a palm tree. It can reach about 12 inches (30 cm) long, and weigh up to 40 pounds (18 kg). The coco de mer, a giant, dark brown seed, has been protected by the government of the Seychelles because of its rarity. The coco de mer tree can grow up to 100 feet (31 m) tall, with leaves measuring 20 ft (6 m) long and 12 feet (3.6 m) wide. So, the correct answer is 'Lodoicea'.