Mexican whorled milkweed, Asclepias fascicularis
Bees absolutely love the flowers on Mexican whorled milkweed.
Blooms: Light pink to white in color. Blooms mid Summer thru Fall. Approximately July 15th to September 30 I see blooms on this plant. Bee activity is extremely high on the blooms. Though the blooms are pale in color their aroma attracts bees and other pollinating insects at an incredible rate.
Seed pods: Once the blooms begin turning to seed pods the plant develops many pods. Pods are thin and long, about 4" long. Pods contain between 50 and 100 seeds on average. Once a pod opens it can spread all the seeds in as short as one afternoon. Seeds spread in the wind as the silk catches the breeze.
Butterflies: Monarchs have been observed laying eggs on this species. I have personally seen this behavior on a plant near the California/Nevada state line. The narrow and numerous leaves make it a time consuming endeavor to search for eggs. I have seen a monarch caterpillar eating the leaves. That caterpillar was at a butterfly house.
View Mexican whorled milkweed observations on iNaturalist
View Mexican whorled milkweed plant information at Wildflower.org
View Mexican whorled milkweed plant information at Plants.USDA.gov