Almost from the beginning, Ms. Ward’s zeal for “reform” and rigorous gardening doctrine earned her the enmity of some longtime members.

First she raised eyebrows by asking board members to address her as “Madam President.” (Ms. Ward said she had requested they use the honorific as practice for formal club meetings, when parliamentary rules dictated that officers be addressed by title rather than by name to avoid making things too personal.)

Then she announced that, among other innovations, like public education initiatives and worm composting, she would be taking a stand against weeds.

Mr. Schuppert’s faction claims she began e-mailing the club with lists of delinquent gardeners, including the much-beloved cultivator of the club’s rose garden, threatening them with expulsion; Ms. Ward says she merely left helpful, if pointed, reminders to weed in the relevant gardens. (She said she used waterproof paper for her notes.) Whatever happened, club members — most of whom were used to more tender handling — were shocked.

“People start to be afraid of having a garden when you have a dictator like that,” Mr. Elbaz said.

The final straw for many came when Ms. Ward declared that the formerly neutral territory known as the border plots, which encircle the patchwork of individual gardens, would be divided up and given to anybody who wanted them, even associates, no waiting list necessary, so that the border could be maintained with the proper shrubbery and florals. It was, full members protested, a violation of the two most basic tenets of the garden club: that one must wait one’s turn for a plot, and thus full-member status (even if it might take three to six years), and that associates may help, but may not own (a longstanding class distinction).

“The real reason for doing that was to get a bunch of new members who were in her thrall,” Mr. Schuppert said.