Nature

Audubon Naturalist Society

Woodend Sanctuary, 8940 Jones Mill Road, Chevy Chase. 301/652-9188 or www.audubonnaturalist.org

• The largest and oldest independent environmental organization in the region.

Hillwood Museum and Gardens

4155 Linnean Ave. NW. 10 a.m.-5 p.m. Tuesday-Saturday. Closed January and national holidays. $5-$12. 202/686-8500; information and advance reservations 202/686-5807 or reservations@hillwoodmuseum.org.

• Spring garden tours. Docent-led tours explore the history of the gardens and identify the scores of plants, including lilacs; irises; Japanese pieris; daffodils; forsythia and spring-flowering shrubs and trees; azaleas; crabapple, dogwood and cherry trees; tulips; and rhododendron. 10:30 a.m., 12:30 p.m. Tuesdays-Saturdays; 2:30 p.m. April 13 and 27. Through June 22. Admission included in estate donation.

Historic Garden Week in Virginia

Annual event, now in its 75th season, sponsored by the Garden Club of Virginia. More than 30 tours of more than 250 gardens, homes and historic landmarks statewide April 19-27. Proceeds go to restore historic gardens and grounds across the state. Local listings follow; for full information on both local and statewide tours see www.vagardenweek.org.

• Alexandria: The Hunting Creek Garden Club and the Garden Club of Alexandria. Walking tour of six properties in Old Town 10 a.m.-4 p.m. April 19. Full-tour ticket $40 ($20 children under 12, babes in arms free) includes six properties with gardens, admission to six nearby historic properties, refreshments. Single property or garden admission $10. Tour-day tickets at the Ramsay House (221 King St., 703/838-4200) or at any of the tour properties. Advance tickets $35 online with credit card (for an additional charge) at vagardenweek.org or at the Ramsay House.

• Fauquier and Loudoun: The Fauquier and Loudoun Garden Club with the Leesburg Garden Club. Driving tour of five properties in the Mosby Heritage Area of Middleburg 1-5 p.m. April 20, 10 a.m.-5 p.m. April 21. Full-tour ticket $35 (children 6-12 half price, children 5 and younger free) includes admission to all five properties. Single-site admission $15 (same discount for children). Tour-day tickets at the Hill School Dornin Science Center, 1753 The Plains Road, Middleburg, and at each house on tour. Advance tickets $30 by mail (see Web site for details), at information centers or online with credit card (additional charge) at vagardenweek.org.

• Fairfax and Great Falls: The Garden Club of Fairfax. Shuttle bus tour, from two parking lots, each shuttling to two homes/gardens in Great Falls 10 a.m.-4 p.m. April 22. Full-tour ticket on tour day $25; single-site admission $15 (children 6-12 half price, children 5 and younger free). Tour-day tickets at Christ the King Lutheran Church parking lot, 10550 Georgetown Pike, Great Falls; on shuttles leaving from the Great Falls Library parking lot, 9830 Georgetown Pike, Great Falls; or at any of the tour properties. Advance tickets $20 by mail (see Web site for details) or online with credit card (additional charge) at vagardenweek.org.

National Aquarium in Baltimore

501 E. Pratt St., Baltimore, at the Inner Harbor. 10 a.m.-4 p.m. Monday-Thursday; 10 a.m.-8 p.m. Friday; 10 a.m.-5 p.m. Saturday, Sunday. Admission $12.95-$21.95, with a range of packages at $14.95-$28.95. 410/576-3800, 410-659-4278, www.aqua.org. Tickets through the Web site or ticketmaster.com, both with service charges.

• Hundreds of exhibits with more than 16,500 animals. Popular exhibits include “Animal Planet Australia: Wild Extremes,” “Frogs! A Chorus of Colors,” “Play! The Dolphin Show” and the new 4-D Immersion Theater. See the Web site for details.

National Aquarium in Washington, D.C.

U.S. Department of Commerce building, 1401 Constitution Ave. NW. 9 a.m.-5 p.m. daily; last admission 4:30 p.m. Closed Christmas and Thanksgiving. Admission $2.50-$5. 202/482-2825, www.nationalaquarium.com

• Animal keeper talks and animal feedings 2 p.m. daily: sharks Monday, Wednesday, Saturday; piranhas Tuesday, Thursday, Sunday; alligators Friday.

National Zoological Park

3001 Connecticut Ave. NW. Grounds open 6 a.m.-8 p.m. daily, buildings 10 a.m.-6 p.m. daily through Oct. 31. Free. 202/633-4800, nationalzoo.si.edu

• Kids’ Farm. New 2-acre exhibit helps children understand where food comes from. Cows, donkeys, goats, vegetable garden. Opportunities to groom the goats and donkeys. Near the zoo’s Rock Creek Park entrance, at the bottom of Olmsted Walk. 10 a.m.-6 p.m. daily through Oct. 31. Free.

Planetarium: David M. Brown Planetarium

1426 N. Quincy St., Arlington. Admission $2, $3. No reservations needed. Doors open 15 minutes before the show. 703/228-6070, www.apsva.us/planetarium

• “Just Imagine.” Exploring “what-if?” questions such as the Earth without a moon, the sun as a different kind of star and more. Ages 10 and up. 7:30 p.m. Fridays, Saturdays; 1:30 and 3 p.m. Sundays. Through April 27.

• Public multimedia programs 7:30 p.m. Friday, Saturday; 1:30 and 3 p.m. Sunday during school year. Stars Tonight program, live interactive talk with the planetarium director and a dome full of stars, 7:30 p.m. first Monday of the month (second Monday when first Monday falls on a legal holiday) during the school year.

Planetarium: The Einstein Planetarium, National Air and Space Museum

Independence Avenue and Fourth Street SW. 10 a.m.-5:30 p.m. daily. Metro: L’Enfant Plaza. 202/633-1000, www.nasm.si.edu/visit/theaters/planetarium. Imax theater schedule: 877/932-4629.

• Planetarium shows: “Cosmic Collisions,” “Infinity Express,” $6.50-$8.50; call for showtimes. “The Stars Tonight — Open Your Eyes to the Skies,” 11:30 a.m. Tuesday, Thursday, Saturday. Free.

Planetarium: Rock Creek Park

Nature Center, 5200 Glover Road NW. 9 a.m.-5 p.m. Wednesday-Sunday. Closed major holidays. 202/895-6070 or www.nps.gov/archive/rocr/planetarium

• The only planetarium in the National Park system. Planetarium shows 1 p.m. Saturday, Sunday for children 4 and older; 4 p.m. Saturday, Sunday for children 7 and older. After-school show 4 p.m. Wednesday. Outdoor evening stargazing sessions once a month April-November at adjacent Military Field, off Military Road.

Second Chance Wildlife Center

7101 Barcellona Drive, Gaithersburg. 9 a.m.-5 p.m. daily. 301/926-9453, www.scwc.org

• The only rehabilitation facility for wildlife in the metro area, offering volunteers the chance to care for orphaned and injured wildlife, especially newborns.

U.S. Botanic Garden

100 Maryland Ave. SW, adjacent to the U.S. Capitol. Conservatory 10 a.m.-5 p.m. daily; National Garden 10 a.m.-5 p.m. through May 31. Free. 202/225-1116, www.usbg.gov

• “An Alphabet Garden of Orchids.” Annual show of hundreds of orchids, including rare and endangered species, from the collections of the U.S. Botanic Garden and the Smithsonian Institution’s Horticulture Services Division. Through April 13.

• “How Plants Work: A Guide to Being Green.” The daily realities of life as a plant. East Gallery. Permanent exhibit.

U.S. National Arboretum

3501 New York Ave. NE. 8 a.m.-5 p.m. daily. Closed Christmas and federal holidays. Free. 202/245-2726 or www.usna.usda.gov

• Ikebana International Exhibit. Annual show of Japanese flower arrangements by the Washington, D.C. Chapter No. 1 of Ikebana International. Free demonstrations by master teachers 1-2:30 p.m. April 12, 13, 19 and 20. National Bonsai & Penjing Museum. 10 a.m.-4 p.m. April 11-20. Free.

• Camellia Show. Judged show sponsored by the Camellia Society. Administration Building. 1-5 p.m. April 12; noon-4 p.m. April 13. Free.

• “Seeking New Horizons for Camellias.” Talk by Dr. William Ackerman, a camellia breeder for 40 years. 1:30 p.m. April 13. Free.

• Full Moon Hikes. Arboretum grounds regardless of weather. 8-10 p.m. April 18-20 (all full), May 18-20 (all full) and June 15-17 (all full). $19. Registration required online or by mail; 202/245-4521 for information.

Washington National Cathedral

Tours of the grounds at Massachusetts and Wisconsin avenues NW sponsored by the All Hallows Guild. Meet at the George Washington statue on Pilgrim Road, on the south side of the Cathedral. All programs free; no reservations required. Programs will be cancelled in the event of heavy rain. Woodlands information line 202/537-2319, www.cathedral.org

• Olmsted Woods walk. Leader Annette Lasley, native plant specialist, focuses on the history and folklore of flowers. 10 a.m. April 24.

• Bird walks. The woods have been restored with ground covers, shrubs and trees attractive to birds and other wildlife. Experienced birder Sheila Cochran leads the way. 8:30 a.m. May 8 and 15.