Ask Mr. Smarty Plants

Texas is rich in milkweeds, Asclepias spp.  Of the 75 species of milkweeds that occur in the US, more than half (42) can be found in Texas.  At least 10 native milkweed species occur in and around Smith County, in east Texas' Pineywoods ecoregion. 

Asclepias amplexicaulis (clasping milkweed) bears follicles (seed pods) 10-16 cm long and 1-2 cm in diameter in the summer.  Asclepias asperula (spider milkweed) bears follicles 4-13 cm long, 1-2.5 cm in diameter from spring through summer.  Asclepias incarnata (swamp milkweed) produces follicles 7-9 cm long, 1.2 cm in diameter in summer and fall.  Asclepias obovata (pineland milkweed) has seed pods to 12 cm or more in length from early summer to early fall.  Asclepias rubra (red milkweed) bears follicles 8-12 cm long and 1-1/2 cm in diameter in summer.  Asclepias stenophylla (slimleaf milkweed) produces seed pods 9-12 cm long in summer.  Asclepias tomentosa (tuba milkweed) forms follicles 10-12 cm long in late summer and fall.  Asclepias tuberosa (butterfly milkweed) makes seed pods 8-15 cm long and 1 to 1-1/2 cm in diameter from spring til autumn.  Asclepias verticillata (whorled milkweed) bears follicles 7-10 cm long and 5-8 mm in diameter from spring until early fall.  Finally, Asclepias viridis (green antelopehorn) produces follicles 6-13 cm in length and 2-3 cm in diameter from spring through early fall.

So Asclepias amplexicaulis may make the champion milkweed pods in your area based on length.  If you factor in girth to find the most massive milkweed follicle, then Asclepias viridis my win by a nose.

Not every species listed here necessarily occurs in Smith County.  However, they have all been collected no farther away than one of the counties adjacent to yours.  So, if conditions are favorable, you might expect to find any of them there.