Ginkgo biloba ginkgo, maidenhair tree

Ginkgo on Escondido Mall during December rains, one of the latest of its species on campus to turn color. Sairus Patel, 10 Dec 2022

Ginkgo seeds (technically not fruits) and leaf. John Rawlings, c 2005

In the fall, the clearest pure yellow is seen displayed on the numerous maidenhair trees, every single one of which growing on campus can then be discovered with ease. Examination of the fan-shaped leaf suggests something a trifle unusual, apart from the resemblance of the shape to the maidenhair fern, and indeed the tree turns out to be a gymnosperm, having a naked, edible seed as with conifers, but antedating today’s conifers. The fallen fruit being messy and smelly, it is customary to plant only male clones.

The trees were planted in Chinese temple grounds from time immemorial for the edible kernels, but for decades the only campus female has been one in the thicket between the Faculty Club and Kingscote Gardens.

In Palo Alto, a beautifully shaped, mature specimen is at 1457 Hamilton Avenue, and ginkgos line Greenwood Avenue between Hutchinson Avenue and Newell Road. A female is in the garden of The Museum of American Heritage at 351 Homer Avenue, near the wisteria-covered walkway.

The first in America date back to the 1780s in Philadelphia, which was in those years the locus of American botanical interest. The ginkgo was brought by Engelbert Kaempfer in 1691 to Utrecht, where a tree from those days is still standing. For colorful and extremely charming and exhaustive background, including a photo of Goethe’s poem to a lady comparing himself to a ginkgo, see the website The Ginkgo Pages by Cor Kwant. The 2013 book Ginkgo: The Tree That Time Forgot by former Kew director Peter Crane has a wealth of information as well.

Ginkgo at Barnum Center (now transplanted 50 feet south due to construction). Sairus Patel, 12 Dec 2016

In the late eighties or nineties, 16 or more ginkgos appeared at the east end of Green Library and by 2001 half of them were bearing cherry-sized yellowish seeds – nursery mistakes can happen. Those trees were removed. The thin layer of flesh, which has an astringent taste, encloses a single, thin-shelled, keeled pit with a satin finish and containing a two-toned kernel that is equally attractive in appearance. A 1½-inch stalk emerging from a leaf axil has two ovules that, by fall, may ripen as a pair, but half will ripen as singles. The female reproductive structure, technically not a flower, has no petals, no calyx, and no pistil – it is just a tiny ovule less than ¼ inch across, with a rounded surface and a nipple that is receptive to pollen. This is a truly primitive “flower,” with ancestry dating back to before the days of insects or other pollinators. The pollen-bearing cones (again, technically not flowers), which grow on separate male trees, have the form of catkins. With dioecious species such as the ginkgo, if you do not want fruit, you try to raise only male trees; on the other hand, if you want fruit, kiwi fruit for example, you need both males and females.

More commonly, flowers possess both male organs (anthers) that produce pollen and female organs (stigmas) that receive pollen; the ensuing seeds are then sheltered in an ovary. This seems like an economical plan, putting the key organs together, except that it tends to frustrate the fostering of genetic diversity resulting from attraction of insects or birds to carry pollen from one tree to another. Avoidance of self-pollination is a key feature of bisexual flowers; it is achieved by temporal, geometrical, or chemical means. A fig encloses over a thousand tiny flowers, male and female, but cross-fertilization is cleverly discouraged by delaying pollen release until the female flowers have passed beyond receptivity. Self-pollination may happen anyhow, and in some cases may be counted upon.

Ginkgo leaves give a glimpse of the origin of leaves as we know them today. There are no netted or anastomosing veins, only repeated forks radiating from the stalk. Eighty or more veins terminate in a wavy edge without converging to an apex as everyday leaves do. Get a leaf of flax, a reed, and a palm leaflet, for close comparison with a leaf from the Green Library ginkgos.

Although the tree is native to China, where it is known, among other names, as yin hsing (silver apricot), the name ginkgo is from archaic Japanese gin-kyo. Fossil leaves are found in Asia, Australia, Europe, and America (as at the Ginkgo/Wanapum State Park on the Columbia River 30 miles east of Ellensburg, Washington) showing that the design dates back 150 million years.

Ginkgo biloba extract is a widely sold supplement, prepared in different ways by various manufacturers.

Name derivation: Ginkgo – silver apricot in Chinese; biloba – two-lobed, in reference to the leaves.