More Plants On Avalon

"...plants whose ancestral seeds arrived with the pioneers had here long ceased to be foreign."
-Poul Anderson, Rise Of The Terran Empire (New York, 2011), p. 659.

Anderson goes on to mention:

grasses;
trefoil;
sword-of-sorrow (see In The People Of The Wind, Chapter Nineteen here);
pine;
harp vine (see In The People Of The Wind, Chapter One here);
jewelleafs (same link as for "harp vine").

Of these, only grasses and pine are imports. Harp vine and jewelleafs have been described before but this might be the only reference to sword-of-sorrow.