A Tale of 2 Grapes

Common grape (Vitis rotundifolia) is a plant that we see very frequently at the Oslo Riverfront Conservation Area and elsewhere.  On sunny trail edges and in disturbed areas it can grow quite zealously.  All grape vines climb by tendrils and can be very vigorous.

On our walk at the Toni Robinson Waterfront Trail (TRWT) on 12/8/2019 led by Terry Greene (Class of 2019), we saw two other plants in the grape family, Vitaceae: peppervine (Nekemias arborea) and possum grape (Cissus verticillata).  Both of these plants are found at the Oslo Riverfront Conservation Area (ORCA), too. The appearance of their leaves, however, is quite different, but both bear “grapes” that are beloved by birds and other wildlife.

Peppervine has coarsely toothed alternate compound leaves that are bipinnate (or tri).  Check out the distinctive purplish coloration of its stems (rachis) …

Its small fruits are purplish when ripe …

Possum grape shown above at TRWT, by contrast, has alternate heart-shaped leaves that feel rubbery.

Though native to coastal central and south Florida, this vine can be frighteningly aggressive and can engulf trees.  Even a small stem fragment can root, and the vine develops thick aerial stems that can reach back down to the ground from on high.  At ORCA it was amazingly aggressive after the 2004 hurricanes that ravaged the canopy.

Its fruits are dark purple or black when ripe and are spread by wildlife especially birds …

Its whitish flowers, shown above, are parasitized by  a smut fungus, Mycosyrinx cissi.  What you see below at TRWT might appear to be flowers but really are the result of this smut fungus which dramatically transforms the flowers producing numerous sterile but attractive branches..

Grapes of all species can be a great food for wildlife but can be rampant.

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