by Deva Brown, Bexar County Master Gardener
I was watching the black pipevine butterflies in my yard, which were flitting around and occasionally landing briefly, but persistently, in one area. Not seeing any flowers there, I wandered over. On closer inspection, I saw the strangest plant I had ever seen. The whole plant was about 5-inches tall, with this weird looking flower and thin grassy looking leaves. It was really hidden in the vegetation. It looked something like a jack- in-the-pulpit, apitcher plant, or an orchid.
But this was dry, sandy south Bexar county, not moist woods or swamps where I would expect to find those plants. I got out my Wildflowers of Texas by Geyata Ajilvsgi which is organized by flower color, but even there, I couldn’t find the identification. What color was the flower really? White, purple, or grey?
Finally, I decided to look up the pipevine butterfly life cycle, since they seemed to really like this plant. I found out that the pipevine family is a host plant, and on closer inspection of that family, was finally able to identify my plant as a Texas native swanflower, or Aristilochia erecta, a relative of the South American native, Dutchman’s pipe (Aristilochia fimbriata). According to the Lady Bird Johnson Wildflower Center, swanflower blossoms are apetalous (they do not have petals), so that small tubular structure you see is actually a protective calyx. Swanflower is generally shorter than 6 inches. It mimics a vine-like grass that can be difficult to spot. “You’re most likely to be led to one by a female pipevine swallowtail seeking to lay her eggs!” And that is how I spotted the plant in my yard, by following the butterfly.
From the Field Notes of the Capital Area Master Naturalists, “Aristolochia erecta is documented as being found across all forty-eight of the contiguous states, but most abundantly found in Texas. It has an elongated tuber-like root, which makes it hard to dig up and transplant. It typically blooms from April to October with blooms being small, purple and brown singular flowers that resemble a cross between a small orchid and a mushroom. The flower top ends with a green tab extending upward, which turns brown and a bit curly later. It is actually easier to spot the bright reddish orange caterpillars of a pipevine swallowtail than the tiny swanflower itself.”
The pipevine flower is pollinated by small flies and gnats that are attracted to its pungent scent (think carrion) for pollination. The resulting seed pod resembles a small ribbed watermelon. As the seed capsule dries, it splits open between the ribs which remain intact, forming a little cage, which the triangular seeds are able to slip through.
The pipevine swallowtail butterfly lays eggs on the plant, but I have no idea how the caterpillars find enough food to eat in my yard, or how the plants are able to produce seeds since the caterpillars are so voracious. But they are present in my yard each year. As you can see in the photo, there are many caterpillars for that little plant, and it was soon eaten. The plants are perennials, with a deep taproot which sustains it through drought, winter and caterpillar attacks.
I have been able to find several areas in my yard where this plant grows, and I am happy when I see the seed pods, knowing that the caterpillars didn’t eat it up before it seeded!
Full or partial sun
Low water usage once established
Check native plant nurseries for availability.
All photos courtesy of Deva Brown, BCMG.