AI Confusion: manzanitas that look alike are different, and manzanitas that look different are the same

Two manzanitas on Fort Ord that appeared to be quite different were growing side by side, branches intertwined. The iNat AI named the one on the right that was past its bloom and beginning to fruit, Arctostaphylos crustacea. And it named the one on its left that was in full bloom, A. tomentosa.
It was a bit hard to photograph the two that day because the clouds were moving quickly and one moment the scene was in deep shade and the next brilliant sunlight, but the manzanita on the right that was past its bloom also appeared to be far greener than the one on the left. Looking at the twigs, both were short haired, but the one on the left was far hairier. Neither appeared to have glandular hairs in my opinion. Looking next at the leaves, the upper surfaces on both plants were shiny and smooth. The undersides were both hairy, but the one on the right was less dense with longer bristly hairs that were bent, tangled, and almost appeared to be branched or frayed. The undersurface of the leaves on the left were much more densely covered with hairs but they appeared shorter, not bristly, and more uniform with less fraying. Both had reddish-grey persistent shredding bark, and appeared to have burls though I would have needed a long handled rake to be sure.

Both plants key to Arctostaphylos tomentosa tomentosa per The Jepson Manual online despite looking quite different to me, both from a distance in color and bloom, and up close in the type and quality of hairyness (Indumentum for those who don't understand English).

• Burls at base of main stem, also above or not; plant sprouting after fire
• Leaves with stomata generally only abaxially, surfaces generally differing in color and/or hairiness
• Old stem bark persistent, gray, shredding
• Twig without glands
• Twig short-tomentose or short-nonglandular-hairy
• Leaves tomentose abaxially

Posted on Μάρτιος 03, 2024 0448 ΜΜ by hkibak