• A mass of dodders feeding off a host plant.parasite: dodder image by Brenton W Cooper from Fotolia.com
  
  Annuals are plants that complete their life cycle in one season. That means they go from seed to flower to seed then die off. This life cycle is an adaptation to harsh conditions during part of the year, yet still gives the plant the ability to utilize the more hospitable seasons to grow and reproduce. Annuals have developed many different strategies to compete with other plants; sometimes they can be quite unusual.
  
  

Rainbow Plant

• The rainbow plant (Byblis liniflora) is a carnivorous annual native to northeast Australia. Rainbow plants are unusual because they are the only carnivorous plant that are true annuals. They trap their prey similar to the more common sundews. The stems, leaves and outer parts of the flowers are covered with hairs, each have a drop of sticky dew on the tip. When an insect lands on the plant, it gets hopelessly trapped, then eventually digested. The plants stay short, under 1-foot tall, and consist of a thin central stem with flat needlelike leaves radiating out sparsely, making the plant look spindly. The flowers are small and colorful with five petals.
  
  Rainbow plants like full sun and moist-to-wet soil. A mix of two parts sand and one part peat works well. To sow seeds, use a 3-inch pot and scatter them on the soil surface, then gently press them in. Wild collected seeds need to be scorched by fire to sprout. They do not like transplanting.
  
  

Dodders

• Dodders (Cuscuta species) are unusual annual plants because they have no roots or leaves and they contain almost no chlorophyll to produce their own food. They live their life as parasites, sucking nutrients from their host plant. Dodders have pale yellow-orange to white stems and look like a mass of spaghetti noodles. They attach to their host by small penetrating nodes called haustoria. When a dodder seed sprouts on the ground, it has about 10 days to find a host and attach or it will not survive. They spread readily by seed that is capable of remaining viable for many years, which makes eradication difficult. Many species are host specific, but some will attack numerous hosts. Dodders are a problem weed across the world in agricultural crops such as alfalfa, clover and potatoes.
  
  

Devil's Claw

• The annual devil's claw (Proboscidea parviflora) has an unusual way of spreading its seeds. The seed pod resembles a bean with a large hook on the end. When it dries and splits open, the hook becomes two sharp, 12-inch-long prongs that entangle themselves in an animal's foot and hitchhike, spreading seeds to a new growing location. It is native to the American southwest and northwest Mexico, where it thrives in desert conditions and even saline soils.
  
  Devil's claw reaches 3 feet tall and may spread to 7 feet in diameter. It has 12-inch-long, roughly triangular-shaped leaves with three to seven lobes. The flowers are produced on slender stems with up to 15 on a stalk. They are pink and tube-shaped, about 3/4 inch wide and 1 1/2 inches long.