Blooming spring: Magnolias and Japanese toads

Blooming spring: Magnolias and Japanese toads

Spring is finally here to stay. For almost all Japanese, the final and definitive act in this seasonal drama is the blooming of the Somei-Yoshino ornamental cherry trees. In the Tokyo region, the hanami flower-viewing parties should begin later this week. Look for office workers laying out their plastic sheets underneath the trees in popular parks and gardens.

For a countryside naturalist, however, the best show in town actually begins a full week earlier. The show itself is held in secluded irrigation ponds and ditches, but the advertising posters can be seen everywhere. These take the form of huge, white, wide-open flowers, packed tightly onto the branches of the kobushi magnolia (Magnolia kobus) trees. The kobushi is a common native woodland species, but is also planted along suburban streets, and in parks and gardens.

Magnolias are considered by botanists to be among the oldest and most primitive flowering plants, with an ancient lineage that can be traced back to the age of dinosaurs. Their structure is quite simple and easy to see. Five or six broad white petals open out to form a safe landing pad for clumsy beetles, which are among the magnolias' main pollinators. At the centre of the flower sit several rings of yellow stamens, and a single green pistil. Usually one or two leaves emerge at the base of the flowers just as they open.

The kobushi magnolias start blooming about a week or 10 days before the ornamental cherries. This puts them right in tune with the breeding schedule of the Eastern Japanese toads, or azuma-hikigaeru (Bufo japonicus formosus). Dozens of these toads collect at ponds and ditches, and the males engage in an incredible free-for-all fight for access to the females. The males kick and throw each other around with reckless abandon and energy. The winner grabs a female just under her armpits, and hangs on for dear life, while competitors try their best to dislodge him. Professional wrestling fans would call this sort of last-man-standing survival battle a "Royal Rumble," but biologists refer to it as "Scramble Competition," and the Japanese as "Kaeru-Gassen."

The males are generally smaller than the females, and are equipped with hard, abrasive pads, called nuptial pads (konin-ryu), on the tips of their fingers. These help the male keep his grip on the slippery female. Like most amphibians, the toads do not engage in actual copulation (kobi). The male, if he is able to maintain his hard-won position on the female's back, squirts his sperm on her eggs as they emerge from her body. This style of external fertilization is technically known as amplexus (kosetsu).

The toad eggs emerge in a long string, together with a chemical substance that after fertilization expands to form a clear gel. The gel keeps the eggs together, and helps prevent desiccation. If stretched out, the egg mass of a single healthy female can measure up to five or six meters in length, and contain several thousand eggs.

Toads are slow and clumsy, but protect themselves with a defensive poison squirted from glands on their back. If swallowed, this poison can kill a small animal such as a fox or feral cat.

Short is a naturalist and cultural anthropology professor at Tokyo University of Information Sciences.

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