Ask Mr. Smarty Plants

There are numerous species and varieties Clematis, but our native Clematis virginiana (Devil's darning needles) is pretty spectacular and worthy of interest.

Mr. Smarty Plants had to look at several sources to find answers to all of your questions, so I will provide you with links to the sites where I found the answers.

First, I went to the NPIN page where I learned that the flowers were scented, and that they were visited by humming birds and butterflies. This link describes the interactions of other birds with Clematis. I also learned that the plant is toxic.

Clematis virginiana is a dioecious species meaning that the staminate (male) flowers and the pistillate (female) flowers occur on separate plants. However, this link to Illinois Wildflowers tells us that there can be vines with all staminate flowers, vines with all pistillate flowers,  and  vines with perfect flowers (having both stamens and pistils). Both pistillate and staminate flowers can be equally showy. The feathery plumes represent the remnant of the stigma of the pistillate flower and is attached to the fruit which is a single-seeded  achene. The plumes can be up to 3 cm long and presumably aid in seed distribution.

Excerpting from the NPIN page we learn this about
Propagation. Description: Higher germination results from stored seeds sown indoors or in a cold frame than from seed sown directly outdoors after collection. Stem cuttings that include at least 2 sets of leaves can be taken any time during the growing season. The fastest method is layering.

You didn’t mention the source of your plants. If you are planting seeds, you should get both male and female plants. If you are buying nursery stock, the people at the nursery may or may not know which plants are females. A sure fire way of determining whether the plant is pistillate or staminate is to wait until it flowers. If you get heads of achenes with feathery plumes, you have a pistillate (female) plant.

The links below are some other sites that I visited that have a good deal of information about this interesting plant.

Missouri Botanical Garden  

Duke University

University of Michigan