Alexandre Henri Gabriel Cassini, the fifth generation of Cassinis

The Cassini and Maraldi family of astronomers was, by the end of the eighteenth century, coming to an end with the pressures on them created in part by the French Revolution. Despite their Italian origins and the scientific nature of their work, they had married into the French aristocracy and were therefore seen as being at least supportive of, or an established part, of French nobility – the natural enemy of the mobs of the French Revolution.

The third child of the six children of Jean Dominique Cassini, Alexandre Henri Gabriel Cassini was born on the 9th May 1781, though I have seen an Italian record of his being born in 1784 – and his name given as Alessandro Enrico. I believe the French record to be correct.

As the older of two sons, Alexandre inherited from his father the title Comte de Cassini and, in the scientific world, was also known as Cassini V, though he did not follow the same areas of science as the preceding Cassinis. It is probable that political intrigue and the difficulties created by those who effectively brought the career of his father, Jean Dominique, to an end were responsible for Alexandre’s being unable or unwilling to follow them in a career in astronomy or cartography. Instead he went into the field of botany.

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A botanical career

The photograph to the right is of one of the plant family named after Alexandre – the Cassiniae asculeata. The genus Cassinia was named in his honour by the Scottish botanist, Robert Brown, 1773-1858, the first Keeper of the Botanical Department of the British Museum.

Alexandre was also an eminent authority on the Asteraceae, the sunflower family. The only other information I have been able to discover about him to date is that the stiff sunflower, Helianthus rigidus, was first described for science by him.

According to wikipedia some genera originally named by him were:

• Brachyscome (1816),
• Carphephorus,
• Dracopis Cassini (Coneflower),
• Emilia Cassini (Tasselflower),
• Eurybia (Cassini) S.F. Gray,
• Euthamia (Nuttall) Cassini 1825 (Flat-topped Goldenrod),
• Facelis Cassini,
• Guizotia Cassini (Niger-seed),
• Helianthus pauciflorus Nuttall ssp. pauciflorus, (Stiff Sunflower), also reported as by Helianthus laetiflorus var. rigidus and H. rigidus (Cassini) Desf.,
• Heterotheca Cassini (Camphorweed, Golden-aster),
• Ixeris (Cassini) Cassini,
• Ligularia Cassini,
• Pallenis Cassini,
• Pluchea Cassini (Marsh-Fleabane),
• Sclerolepis Cassini (Sclerolepis), and
• Youngia Cassini (Youngia).

In addition to his botanical interests he was a magistrate and an advisor at the Supreme Court of Appeal with a particular interest in teaching.

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Marriage

Alexandre married his cousin, Catherine-Elisabeth Agathe de Riencourt, who was born in 1783, though I have not yet determined the date of their marriage. Nor am I sure of her name as I have also discovered her as Marie-Catherine-Elisabeth de Riencourt, the fourth of six children of Louis-Henry de Riencourt and Elisabeth-Charlotte Cassini, daughter of César François Cassini, Cassini III. Whatever her name, Catherine-Elisabeth outlived Alexandre, dying on the 5th April 1861.

I have found an address for the Comtesse de Cassini around 1839, a few years after her husband’s death. She appears in a listing of those who have supported a religious organisation, the Abbaye du Gard, a ‘pious foundation of the twelfth century’. Her address is given as Rue de l’Abbaye, 11 in, I would assume, Paris.

According to a site listing the numbered collection in the Bibliothèque Nationale de France, Alexandre published the following:

• Opuscules phytologiques, first collection, in 1826,
• Opuscules phytologiques, second collection, 1826,
• Talleau synoptique des synanthérées in 1829, with
• Opuscules phytologiques, a third or supplementary volume which was posthumously published in 1834.

His first publication earned him entry as a Member into the Academy of Science in 1827, and a promotion to Associate or Pensioner in 1831.

Alexandre Henri Gabriel Cassini, vicomte de Cassini, died of cholera on the 16th April 1832 at the age of fifty. He is generally considered to be the last of the French Cassinis.