Re: Why are the tulips spreading by bulbs, and not by seeds ?

Tulips can reproduce by seed but hybrid tulips will not produce true from seed. 
Reproduction by bulbs is more foolproof than by seed. First, seed reproduction 
requires successful cross pollination. If the weather is bad, the insects 
needed for cross-pollination may not be active. Second, the seeds have to 
mature and not be eaten. Most gardeners snap off the developing seed heads to 
conserve energy for the bulbs. Third, the seeds have to receive proper 
environmental conditions for germination, and the seedlings have to survive for 
several years until they are old enough to bloom.