The sweeping bow of the tulip may be one of its most alluring charms, but it presents a challenge to the flower arranger. To arrange tulips to the best effect, first straighten curved stems by rolling the entire bunch of flowers inside newspaper or brown paper and plunging it into cool water. Because cut tulips will droop, either pack them tightly in an arrangement or give them room to move gracefully in a bigger vase. Hybrid tulips, such as parrot tulips, make outstanding cut flowers. (Species, or nonhybrid, tulips tend to grow low to the ground, like crocuses, and are best enjoyed outdoors.) Parrot tulips bloom mid- to late-season with brilliantly colored petals that are feathered and scalloped. Martha uses the pink-petaled 'Erna Lindgreen' parrot tulip and the antique rose-colored 'Rai' for a springtime arrangement.