A Gardening Journal

Today in the Garden of a Lifetime: Virginia Cup Plant



Quick: Plants with square stems?  Salvias, often, as well as their cousins, the mints.  Here's another: The immense perennial daisies, the silphiums.  Eight, ten, twelve feet tall, they stay upright, in part, thanks to their square stems, which are much more rigid than if they were the same diameter and just round.


Silphiums are renowned for their warm-season displays of foliage and flowers.  Why not their cold-season display of square stems?  The stem above is part of the huge clump below, whose tall stems are crowned by the remains of their branched display of yellow daisies.  This is one of the "perfoliate" silphiums, whose paired leaves grow all around the stem that seems to spear upward through them.  So speared, the large leaves don't drop away in the Fall.  Drat.




But in five minutes, I can slide my lightly-closed hand down each rigid stem, stripping the brown and now-brittle leaves away.  After a few months of puttering elsewhere in the huge beds of my gardens, getting this close again to the clump of Silphium perfoliatum var. connatum also enabled me to discover just what had happened to the green-handled trowel I set aside, in August, during an all-hands-on-deck bout of weeding.




Trowel retrieved, stems stripped of leaves, the silphium clump has acquired its maximal cold-weather interest.  Without the leaves to catch snow and ice, the stems may well stay in place until Spring.




Here's how to grow this immense perennial's remarkable cousin, prairie dock.  The two have the same interest in full sun, and the same flexibility when it comes to soil.  Prairie dock's flowering stems are leafless, but can be even taller than the leafy stems of Virginia cup plant.  Alas, they are round, and have none of this silphium's durability in Winter.


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