Including Hydrophyllaceae of Michigan Flora.
Members of this family in our area are generally rough-pubescent herbs with radially symmetrical flowers, deeply 4-lobed ovary, and alternate leaves. Any exception to these features is noted in the keys or text. The inflorescence is technically cymose, but usually develops in a one-sided way that results in the axis being coiled at the tip; as this straightens when fruit develops, the inflorescence can resemble a spike or raceme. The three genera (Ellisia, Hydrophyllum, and Phacelia) placed in the Hydrophyllaceae in Michigan Flora lack the deeply 4-lobed ovary.
Features of the nutlets (one normally developing from each lobe of the ovary if all ovules have been fertilized) are traditionally used in keys, but in our limited flora features easier to see can usually be emphasized for identification. Hence, the keys here de-emphasize nutlet characters, especially those of the attachment to the base of the style. Many species have long flowering periods, so fortunately specimens with flowers at one end of the inflorescence and at least immature fruit at the other end are commonly collected.
Brunnera macrophylla (Adams) I. M. Johnst., Siberian bugloss, may seed in where it is cultivated. It has small blue flowers but differs from Myosotis in its rugose rather than smooth nutlets; it has large basal leaves with cordate to reniform blades and long petioles.
1. Leaves shallowly palmately lobed to deeply pinnately divided.
2. Flowers on solitary pedicels opposite alternate leaves; cauline leaves at lowest nodes opposite.
2. Flowers in terminal inflorescences; cauline leaves all alternate.
3. Basal and lower cauline leaves long-petioled (petioles over 5 cm long); leaf blades shallowly palmately lobed or deeply pinnately lobed with lateral segments over 1.2 cm broad.
3. Basal and lower cauline leaves sessile or on petioles less than 2.5 (–5) cm long; leaf blades pinnatifid, with lateral segments (excluding teeth) less than 0.8 cm broad.
1. Leaves simple, entire.
4. Corolla bilaterally symmetrical (lobes unequal), with some or all filaments much longer than the lobes.
4. Corolla radially symmetrical, with all filaments (and usually anthers) shorter than corolla lobes.
5. Corolla rotate, ca. 16–25 mm broad, the inconspicuous tube saucer-shaped; anthers conspicuous, ca. 5–7 mm long, on very short, appendaged filaments.
5. Corolla funnel-shaped to bell-shaped or salverform (or less than 16 mm broad), the limb ca. 1–22 mm broad; anthers shorter (less than 4 mm), the filaments various.
6. Style conspicuously exserted, longer than calyx and at least the tube of the corolla; anthers ca. 1.5–3.5 mm long; corolla (9–) 10–22 (–26) mm long, ± cylindrical, even if expanded above the tube the lobes barely if at all spreading; nutlets never bristly; corolla blue (or pink) except dull white in Lithospermum.
7. Corolla dull white or greenish, the lobes acute and longer than broad; inflorescence with a bract at the base of each pedicel.
Lithospermum (in part)
7. Corolla blue (or pink), the lobes obtuse or rounded and broader than long; inflorescence with bracts none or only at the base.
8. Corolla glabrous; calyx lobes glabrous or with mostly appressed hairs.
8. Corolla puberulent outside; calyx lobes hispid with spreading bristles.
6. Style ± inconspicuous, usually shorter than the calyx and not exserted beyond tube of corolla (exceeding calyx and sometimes corolla tube in long-styled Lithospermum, with yellow salverform corollas, and in Anchusa); anthers 0.3–2 mm long; corolla funnelform or salverform, the lobes (especially if corolla over 10 mm long) usually spreading; nutlets in some species bristly; corolla variously colored (blue or not).
9. Stigma distinctly 2-lobed; corolla yellow to orange-yellow or whitish, never blue or reddish; flowers sessile or on very short pedicels (even in fruit the pedicels shorter than the calyx), each subtended by a bract or leaf; nutlets smooth and shiny or with tiny pits (rugose-pitted in Buglossoides).
10. Plants deep-rooted perennials; nutlets whitish, ± shiny, at most with tiny pits.
Lithospermum (in part)
10. Plants tap rooted annuals; nutlets gray-brown, rough-rugose.
9. Stigma unlobed (2-lobed in the blue-flowered Anchusa); corolla blue to pink or maroon or white (not yellow, except at most for a yellow “eye” or for young corollas of Myosotis discolor); flowers usually on pedicels exceeding the calyx when mature, or nutlets conspicuously rough or bristly, or pedicels mostly (or all) bractless.
11. Pedicels each with a bract (though this often supra-axillary).
12. Corolla 8–16 mm broad; nutlets only ridged or wrinkled, each set into a collar-like ring at the base.
12. Corolla less than 5 mm broad; nutlets bearing bristles (or slender prickles) minutely barbed at the tip, without collar-like ring at the base.
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11. Pedicels all or mostly without bracts.
13. Nutlets smooth or rugose-tuberculate, without elongate bristles, nearly or quite concealed in the calyx; corolla blue or white, often with yellow “eye” at the center (rarely all yellow).
14. Leaves linear, opposite (at least at middle and lower nodes); corolla white (except for yellow eye), ca. 9–10 mm broad; nutlets rugose-tuberculate; plant a rare waif.
14. Leaves ± elliptic, all alternate; corolla usually blue (except for eye) or sometimes white (rarely pink or yellow), 1–9.5 mm broad; nutlets smooth and shiny; plants (at least some species) widespread.
13. Nutlets bearing prominent bristles with barbed tips, early surpassing the calyx as they ripen; corolla mostly blue or dull red, sometimes white, without yellow (or other) “eye.”
15. Corolla red or uppermost leaves ± clasping; nutlets oriented horizontally, with bristles over all faces including the conspicuously exposed ventral face.
15. Corolla blue (or white) and uppermost leaves not cordate-clasping; nutlets ± erect, with bristles only along the margins of the exposed (dorsal) face (and in one species, on that face).
16. Pedicels promptly becoming reflexed after flowering; leaf blades elliptic, with evident lateral veins; bracts toward base of inflorescence much exceeding the flowers and fruits.
16. Pedicels ascending even in fruit; leaf blades linear to lanceolate, without evident lateral veins; bracts toward base of inflorescence usually about equaling the flowers and fruits, or shorter.