Aiea Orchid Club Inc.: 16th annual orchid show runs 9 a.m.-8 p.m. today and tomorrow, and 9 a.m.-4 p.m. Sunday, Aiea Elementary School Cafetorium. Lectures and demonstrations include general orchid culture by Jim Ferguson, 2 p.m. today, by Doug Schafer, 6 p.m. tomorrow, and by Marty O'Day, 11 a.m. Sunday; honohono orchid culture by Richard Inouye, 6 p.m. today, and by Lloyd Esaki, 11 a.m. tomorrow; and an anthurium culture by Kenneth Hayashi, 2 p.m. tomorrow. Cost: $1. Call 487-7625.

Foster Botanical Gardens, 522-7060: "Na Waiwai i Ka La'au o Hawai'i Nei," the richness in the plants of Hawaii, is a combination of workshops and entertainment being held through Sunday; costs $5 per day. Demonstrations and entertainment, 10 a.m.-4 p.m. tomorrow and Sunday. Demonstrations include the usage of plants in building materials, medicinal plants, and plants for food, clothing, arts and crafts. Call 373-2759.

Halawa Xeriscape Garden, 527-6113: Free admission to garden of dry-land plants at Halawa Industrial Park 10 a.m.-2 p.m. Saturdays and Wednes-days. Guided tours free on Thursdays and the last Saturday of each month; call 527-6113 for an appointment.

Hawaii Tropical Flower Council, P.O. Box 4306, Hilo, 1-808-961-5555: Monthly meeting, 10 a.m.-3:30 p.m. Thursday, Komohana Ag Complex Room B, 875 Komohana St., Hilo.

Ho'omaluhia Botanical Garden, 233-7323: Learn about rain forest plants 10 a.m. Saturdays and 1 p.m. Sundays. Free. Bring walking shoes, bug repellent, rain gear and a picnic lunch. Also, compost workshop, 9:30-11:30 a.m. fourth Saturday of the month. Bring walking shoes, insect repellent, rain gear and work gloves.

Lyon Arboretum, 3860 Manoa Road, Honolulu, 988-7378: "Culture and Care of Dendrobium Orchids" with Ed Mersino, 9:30-11:45 a.m. tomorrow, downstairs classroom. Cost: $15.50. Call to register.

Urban Garden Center, 453-6050: Gardening series classes 9:30-11:30 a.m. Wednesdays, 962 Second St. Wednesday's topic is lychee Costs $5. Call to register.

Wahiawa Botanical Garden, 621-7321: Hands-on gardening, 9-11 a.m. Wednesdays. Free.