Plant species within a family vary greatly in their chemical makeup. Some Senecio (cf. http://sankey.ws/senecio.html) have so few alkaloids that they are used in salads, some have so much that a single mouthful will kill a horse within an hour. Same with nightshades (tomatos are nightshades). Same with mushrooms. And, same with milkweeds.
Plant species within a family vary greatly in their chemical makeup. Some Senecio (cf. http://sankey.ws/senecio.html) have so few alkaloids that they are used in salads, some have so much that a single mouthful will kill a horse within an hour. Same with nightshades (tomatos are nightshades). Same with mushrooms. And, same with milkweeds.
Asclepias is a genus not a family. All of which are toxic!!!