- Madder family, [159]
- Mallow, [145], [146]
- Mallow family, [145]
- Malva, [146]
- Malvaceae, [145], [146]
- Mammoth clover, [141]
- Many-seeded goosefoot, [126]
- Maple-leaved goosefoot, [125]
- Marsh elder, [167]
- Marubium, [154]
- May-weed, [161]
- Medicago, [139], [140]
- Melilotus, [140]
- Mexican tea, [125]
- Milfoil, [160]
- Milkweed, [149]
- Milkweed family, [149]
- Millimeter, see last page of this bulletin
- Mint family, [154]
- m. m. Millimeter, see ruled lines on last page, [139]
- Mollugo, [128]
- Morning-glory family, [150]
- Mossy stonecrop, [138]
- Motherwort, [154]
- Moth mullein, [156]
- Mouse-ear chickweed, [129]
- Mouse-ear hawkweed, [167]
- Mullein, [156], [157]
- Musquash-root, [148]
- Mustard, [133], [134], [135]
- Mustard family, [132]
- Narrow-leaved dock, [122]
- Narrow-leaved hawk's beard, [165]
- Narrow-leaved plantain, [158]
- Nepeta, [154]
- Neslia, [137]
- Nettle family, [119]
- Nettle-leaved vervain, [153]
- Night-flowering catchfly, [130]
- Nightshade, [156]
- Night-shade family, [155]
- Nonesuch, [139]
- Nut-grass, [118]
Ob-lan´ce-o-late, lanceolate in form, but tapering toward the base more than toward the apex.
Ob´long, longer than wide with nearly parallel sides. Compare Oval.
Ob-o´vate, a flat body broader toward the apex than the base. See Ovate.
Ob-o´void, a solid body broader towards the apex than the base. See Ovoid.
Ob-tuse´, having a rounded end or apex; blunt.
O´val, about twice as long as broad, with regular curved outlines, broadly elliptical.
O´vate, like a longitudinal section of an ordinary hen's egg, with the attachment, if any, at the broad end.
O´void, the shape of a hen's egg and attached, if at all, at the large end.
- Paint brush, [167]
Pa´le-a, Pa´let, the upper bract which with the floral glume incloses the flower in grasses.