Even in Tokyo there is such a place: a park with large open spaces, where a whole family can enjoy picnics, barbecues, camping, flowers and beautiful trees, catch fish and watch birds. Look no further than Mizumoto Park.

Located in Katsushika Ward, with an area of 68.2 hectares, Mizumoto Park was designated in 1975 as the Edogawa Waterway Metropolitan Natural Park. Though many of Tokyo's parks involve water, this one is, frankly, a wetland. The Edo River flows approximately 1 km east of the park; to the north flows the Obagawa, a short tributary of the Nakagawa, which itself flows 2 km to the west. The park was first opened to the public April 1, 1965, but like many parks in Tokyo has its interesting historical aspect.

Over 270 years ago, Koaidame pond was dug, by hand, to serve two functions: to control flooding caused by the old Tone River, and to serve as a reservoir for the town of Ka-tsushika and Edo city.

The park may remind people of Holland, because it is so flat and so wet. Needless to say, the plants in Mizumoto Park, both cultivated and naturally occurring, are moisture lovers. Irises lead the way. The park has the largest iris collection in Tokyo: over 200,000 plants from 80 different species and cultivars, in special beds covering over 9,500 sq. meters. The irises are at their best in early summer, when Katsushika Ward sponsors an iris festival.

The Japanese iris (hana-shobu, Iris ensata) dates back to the Tokugawa Period (1603-1867), when many cultivars of iris were raised in Edo, and you can still see the Edo cultivars today, as well as Izu iris and Higo iris (from the old name for Kumamoto Prefecture in Kyushu).

Irises come in many colors including purple, red-purple, pink and white. Some varieties show marginal variegation (fukurin), others have variegated leaves, semidouble or double flowers. They are perennials, classified as emersed plants (chusui-sho- kubutsu), plants which grow up out of the water. Emersed plants are characteristic of wetlands where soil is water-covered or saturated.

Native irises in Mizumoto Park include the Japanese water iris (no-hana-shobu, Iris ensata var. spontanea), one of the parents of the standard Japanese iris. The flowers are reddish-purple with a yellow blotch at the base of the outer sepal. Another native, kakitsubata (Iris laevigata) is also purple, but instead of a yellow blotch on the outer sepal it has a white one. Both species grow wild in shallow ponds and marshy areas all over Japan.

A dawn-redwood woodland at Mizumoto commemorates Emperor Meiji with over 2,000 trees, close together near the pond. Dawn redwoods (Metasequoia glyptostroboides) are living fossils that were thought to be extinct until a few trees were discovered growing in western Hubei Province in China by Wang Fa-tsuan in 1945. Though conifers, dawn redwoods are deciduous, and in autumn the needles turn brick red before falling. The small, soft needles line the twigs in a herringbone pattern. There is only one known species in this genus; indeed, we're lucky to know this one.

Mizumoto Park is well known for its long avenue of Italian or Lombardy poplars (Populus nigra var. Italica). The planting of these tall, narrow deciduous trees began in 1973; now there are over 290 poplars, some as tall as 20 meters. The origin of these impressive trees is unclear, but is thought to have been Lombardy in northern Italy, from which they spread during the late 18th century.

On a sunny day in January, the poplars and the dawn redwoods were bare, and all the moisture-loving flowers had died down for the winter. Birdwatchers were patrolling the park on their bicycles, elaborately mounted with heavy tripods supporting expensive long-range camera lenses. The bird sanctuary likewise is close to the pond, and offers three specially constructed hides to observe the over 100 different types of mostly water-loving wild birds that live or winter over in Mizumoto Bird Sanctuary.

The trees seen through the observation holes in the hide are completely covered with what looks like snow, but is in fact bird guano, mostly from the great cormorant (kawa-u, Phalacocorax carbo). There are four species of cormorant in Japan, diving birds with long necks and hooked bills, long tails and webbed feet, living in colonies in trees close to ponds, rivers or estuaries. They are large birds; the blue-black great cormorant has a wingspan of 135 cm.

The northern goshawk (o-taka, Accipiter gentilis) is occasionally seen at Mizumoto; you will know this noble bird (as its scientific name assures us) by its blue-gray colors, with brown stripes across its breast. During the winter over 500 marsh ducks (kamo) live here, notably the handsome mallard (magamo, Anas platyrhynchos). The common kingfisher (kawasemi, Alcedo atthis) is a year-round resident of the park, but shy; it may be observed in the main bird sanctuary or in the kingfisher sanctuary close to the western gate.

In the center of the park a large lawn covers some 10 hectares, where January finds plenty of people flying kites. Close by, the Green Advice Center lives up to its name: Children and adults alike may tackle the nature quiz; you can consult the staff on problems you are having with your own garden, or find out any interesting details about the park and its plants you may wish to know. There is a large aerial photograph of the park, plus historical photographs showing the area's appearance 100 years ago.

Close to the entrance near the Mito Kaido road are the remains of Suga Shrine, once an important shrine in the area. In 1942 it was relocated -- to where no one seemed to know, other than "close to the Mito Kaido road."

By the ruins of the shrine lies Gonpachi Pond, where the asaza waterlily (Nympha peltata) occurs naturally. This waterlily can be found growing in ponds or shallow lakes all over Japan except Hokkaido. The shiny green leaves float on the surface of the water and among them, from May until October, the 4-cm yellow flowers.

The park's marsh collection includes many varieties of sacred lotus (hasu, Nelumbo nucifera), which has been cultivated for over 2,000 years. It is native to the Old World from southeast Europe through tropical and subtropical Asia to Australia. The lotus is not considered native to Japan, but in 1951 seed was discovered in a deep mud layer in Kemigawa, Chiba Prefecture, indicating that long ago it did in fact grow naturally here.

Today there are some 70 or 80 cultivars of the sacred lotus, and new cultivars are still being imported. July-August is the time to see the lotus in full bloom. The large leaves rise a meter or more above the surface of the water; the flowers are 15-20 cm across, in colors from yellow to pink and white, and semi-double and double flowers are seen.

The opposite side of the pond belongs to Saitama Prefecture, and, interestingly, there is a park there too, called Misato Park, dedicated by the Saitama prefectural government in 1984, with an area of 16.2 hectares. The Tokyo Parks Department brochures for Mizumoto Park, however, do not even mention that the other park exists.

Is it too hard to imagine a small boat that could ferry visitors across the pond? Should not future maps show the park as what it is: one large, 84.4-hectare green space?

For Mizumoto Park and Bird Sanctuary, from Kanamachi Station on the Keisei or Joban Line take the Keisei bus bound for Nishi-Mizumoto and alight at Mizumoto Koen-mae bus stop. From the bus stop the central entrance is a seven-minute walk. There is also parking for 1,300 cars, not free.

For further information call the park at (03) 3607-8321 or the Green Advice Center at (03) 3600-6417. For information on camping and barbecues call (03) 3627-5201.

Saitama's Misato Park telephone number is (0489) 55-2067.

Wear a good pair of walking shoes and bring a flask of