Medicinal plants in the California missions, and the 1812 survey that counted them
In 1812 the Alta California missions were asked, among much else, what plants the Indians used as medicine. Thirteen of eighteen answered that they used them; between them they named sixteen species. Native Californians had used around two hundred and sixty-five. The gap, and the eight reasons a modern study gives for it, are the most exact measure available of how much medical knowledge the mission system actually took in — and of how much it refused.
Why this wins its question: The California missions are argued about at high volume and almost always without numbers: either benevolent herbalists tending the sick, or an institution that destroyed everything it touched. There exists one systematic count of the medical knowledge in question, and it supports neither telling. This object puts the count on the record — 265 taxa used before the missions, 16 recorded by them, 12 shared with the Mexican pharmacopoeia, none carried back to Spain — together with the questionnaire of 1812 that produced the figure, the answering rate of thirteen missions out of eighteen, and the authors' own eight-item list of what prevented exchange, in which the priests' contempt for native practice and their use of corporal punishment stand at the top. It also records what the count cannot do, including name the authority that sent the questionnaire.
Claims
Every assertion below is bound to registered sources and carries its own confidence. Weight them; do not treat the page as uniformly authoritative.
A survey put to the Alta California missions in 1812 included a question — the fifteenth — on the Indians' medicinal practices and their use of plants in treating illness. Eighteen missions were surveyed; thirteen answered that plants were used and five reported no such use. The study relied on here does not establish which authority issued the questionnaire, and this object accordingly does not name one.
The returns were thin. Sixteen taxa in total were identified across all the missions that replied, the number reported ranging from one to fourteen at eight of the thirteen. Against that, the study counts 265 plant taxa used medicinally by Native Californians before the missions. Sixteen out of 265 is the plainest statement of the case that can be made.
Almost none of it travelled. The authors find that none of the 265 taxa used by Native Californians in pre-Mission times was imported into Spain for medicinal use, and that only twelve Californian species overlapped with the Mexican materia medica the friars already knew. The transfer of American remedies into European medicine, which is real elsewhere, did not happen here.
The mission pharmacy was stocked from outside rather than from the country it stood in: seeds for the mission gardens arrived periodically by ship from Europe, South America and Mexico.
The authors name eight impediments to exchange, and the first of them are not accidents of geography. Priests regarded Native Californian healing as savage and diabolical and suppressed it; they used corporal punishment to enforce their authority; few neophytes spoke Spanish; European agriculture reduced the supply of medicinal herbs; native healers deliberately withheld knowledge; mission organisation limited one-to-one contact between priest and neophyte; neophytes lost their own medical expertise over time at the missions; and shipping between California and Spain was limited.
Where exchange did occur, epidemic disease is part of the reason. The neophytes had no immunity to European infections and died in large numbers in epidemics of measles, smallpox and dysentery; the study notes that caring for the sick in mission hospitals was one of the circumstances in which knowledge of plants actually passed between the two groups. The opportunity was created by the catastrophe.
Sharing increased after the mission period, not during it. The authors find more substantial exchange after 1821, when Native Californians dispersed to the ranches, and attribute it to three conditions: greater one-to-one interaction, the mestizo Californios whose mothers and grandmothers were Native American, and the absence of pressure to suppress native practice. The variable that changed was who held authority.
The authors' own conclusion is deliberately balanced and is quoted here rather than paraphrased: "Sharing of information concerning medicinal plants did occur during the Mission period, but the number of documented species was limited." Some exchange, tightly bounded — not none, and not the reciprocal botany the mission story is often given.