The red three-leaved plant, second on fol42r of the Voynich Manuscript is puzzling. The first plant on the page seems to be Arum. Steve D here proposed Arum Italicum and I like his ID - European bog plant - wetlands plants seem well represented in the VMs - from the water lily, twin flower,sundew, bog rosemary, herb Paris, marsh cinquefoil... There is a three-leaved plant shaped like the one in the VMs that often appear in the neighborhood of the Arum in the wetlands - the Three-leaf Goldthread (Coptis trifolia). However, there's no much redness to it - could be wrong about this.
Steve D's proposal has the right shape and color, but the wrong continent (I am kidding) - North American Frangrant Sumac (Rhus aromatica).
Another option based on shape and color for the red three-leaved plant on the VMs 42r may be the wild strawberry.