What plant is named for its stiff, scratchy leaves and bears showy purple or white cascading flowers?

It's the sandpaper vine. If you touch the curiously rough leaves, you'll think you're touching shark skin or sandpaper. In fact, in some parts of Asia, the leaves are sometimes used for sanding or filing.

The plant is actually native to areas from Mexico to South America, but is grown for its ornamental value in many tropical areas of the world.

This woody, twining vine needs to grow on a sturdy fence, arbor or trellis for support. Trimmed periodically, the sprawling nature of this vine can be contained, and yet kept natural looking.

This plant flowers best when grown in full sun, and when it does flower, it's eye-catching. The vine is covered with nearly footlong sprays of flowers, which cascade downward and are either purplish-blue or white. Purple flowers are common; the pure white is considered rare.

Individual flowers are small. In the purple form, the tiny petals, only about 1/4-inch across, are a deep, dark color in the center. Beneath them are five narrow, light bluish-purple sepals that radiate outward. (Sepals function to protect the petals and reproductive parts of the flower.)

If you walk or drive past Foster Botanical Garden along Vineyard Boulevard, you can't miss the glorious display when the white sandpaper vine is in flower. This plant is mature, and has had many years to attain its height and physical sturdiness.

The smaller purple form growing next to it is only a few years old, brought from Wahiawa Botanical Garden. It began flowering last year. The two plants make a nice contrast when they bloom side by side.

I've always thought that the white flower sprays would make a perfect bridal bouquet, just by themselves. However, the flowers wilt quickly after being picked, so it's best to admire them on the vine.

The flower petals quickly fall off, leaving only the pinwheel-like sepals, which enclose the seeds. Then the color fades and the sepals turn brown and become paper-thin and stiff. When they fall off the vine, sepals twirl like the blades of a helicopter as the breeze carries them away.

Touch them — they feel like sandpaper, just like the leaves.