Nehemiah Grew, Plant Reproduction, and Comparative Anatomy

Scientists who aim to reconstruct past climates and environments make use of pollen—the mass of grains produced within the anther of a flower that carry the sperm. Every pollen grain has a tough protective coat that can survive in the soil for many years, and scientists are able to retrieve stored pollen grains from the soil and identify the plants that produced them. That allows them to list the plants that grew in that place at a particular time in the past. Identifying the plants allows the investigators to construct a picture of the environment at that time, and since every plant has its own climatic requirements it also reveals the type of climate that existed then. This work is possible because the size, shape, and surface markings on pollen grains are characteristic of a plant family and often of a genus or even a species. The study of pollen grains and the spores of nonflowering plants is called palynology, and it has developed from the work of an English 17th-century plant anatomist and physiologist Nehemiah Grew (1641–1712).

Grew published his most important work in 1682. It was entitled Anatomy of Plants and consisted of four books: Anatomy of Vegetables Begun, Anatomy of Roots, Anatomy of Trunks, and Anatomy of Leaves, Flowers, Fruits and Seeds. It had 82 plates and seven appendixes dealing mainly with botanical chemistry. The work was largely a collection of papers and articles Grew had written previously. Grew maintained that every organ of a plant had two parts, a ligneous—woody—part and a pithy part, or parts similar to these. Grew's pithy part was composed of unspecialized plant cells with air spaces between them, a type of tissue for which he invented the name that is still used today, parenchyma. Grew also called the rudimentary root that emerges from an embryo the radicle and the shoot the plume. The term radicle is still used, but the plume is now called the plumule.

Chlorophyll is the green pigment that plants use to capture light photons in the first stage of photosynthesis. Nehemiah Grew was the first person to extract chlorophyll from plant tissue; he dissolved it in oil. He noted that the protective scales on buds overlap like the tiles on a roof, and that this arrangement economizes on space. He studied tulip flowers while they were inside their buds, examined the way cotyledons are folded inside their seed, and found that “bee bread” is made from pollen grains.

Nehemiah Grew was born in September 1641 at Mancetter, a village in Warwickshire, not far from Coventry in the English Midlands. His father, Obadiah Grew (1607–88), was vicar of St. Michael's Church in Coventry. Nehemiah Grew studied at Pembroke College, University of Cambridge, graduating in 1661, then moved to the Netherlands to study medicine at the University of Leiden, where he qualified as a physician in 1671. He returned to England and practiced medicine in Coventry for a short time, but from 1664 he had been redirecting his training in animal anatomy toward plants. In 1670 Grew wrote The Anatomy of Vegetables Begun (later part of his larger work), an essay that caught the attention of Bishop John Wilkins (1614–72), who was the first secretary of the Royal Society. On Wilkins's recommendation Grew was elected a fellow of the Royal Society in 1671. The following year he moved from Coventry to London, where he established a large and successful medical practice. Grew became secretary of the Royal Society in 1677 and was editor of Philosophical Transactions in 1678 and 1679. He died in London on March 25, 1712.