Philadelphus microphyllus |
Philadelphus mearnsii |
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little leaf mock orange, small-leaf mock orange |
Mearns' mock orange |
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Habit | Shrubs, 5–12(–20) dm. | Shrubs, 5–15(–40) dm. | ||||||||||||||||||||
Stems | copper to reddish brown, stiffly to loosely branched, appressed villous-sericeous, ± strigose, hairs often red-gland based, or glabrous; epidermis soon or tardily deciduous exposing cortex and striate bundle caps; bark grayish; internodes (0.1–)1–2.5(–6) cm; short-shoot spurs not present; axillary buds hidden in pouches. |
tan-brown, weathering gray, striate, stiffly divaricately branched, strigose-sericeous; internodes 0.1–3.5 cm; short shoots often present; axillary buds exposed. |
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Leaves | petiole 1–2(–4) mm; blade greenish or whitish abaxially, green adaxially, linear-lanceolate, narrowly ovate to ovate, (0.5–)0.8–3(–5.5) × (0.2–)0.3–1.3(–3.3) cm, herbaceous to coriaceous, margins usually entire, rarely sparsely serrulate, plane or revolute upon drying, abaxial surface short sericeous-strigose, or sericeous-villous with longer hairs, or with ascending to erect hairs, sometimes with dense to moderate understory of slender curled hairs, adaxial surface glabrous, glabrate, ± sericeous-strigose, villous, or with erect hairs. |
petiole 0.5–4 mm; blade green or gray-green abaxially and adaxially, oblong-lanceolate, linear-lanceolate, or elliptic to ovate, 0.5–1.7(–3) × 0.1–0.6(–1.1) cm, coriaceous, margins entire, ± revolute, surfaces ± equally moderately strigose, hairs appressed, coarse, 0.2–0.6(–0.9) mm, without understory of coiled-crisped hairs; veins inconspicuous. |
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Inflorescences | usually solitary flowers, sometimes 3–5-flowered cymes. |
flowers solitary, produced from previous year's long shoots, often appearing axillary. |
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Pedicels | 0.5–3 mm. |
0.5–2 mm. |
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Flowers | hypanthium glabrous, sericeous-strigose basally or throughout, or weakly to densely villous to densely lanate with mixed strigose and villous vestiture, with understory of slender curled hairs; sepals ovate to lanceolate, (2.5–)4–8.5(–10) × (2.5–)3–4.3(–5) mm, apex acute to acuminate-caudate, abaxial surface glabrous, sericeous-strigose, or weakly to densely villous to densely lanate with mixed strigose and villous vestiture, with understory of slender curled hairs, adaxial surface glabrous except villous along distal margins; petals white [marked purple near base], oblong-obovate to broadly ovate, (5.8–)7–16(–21) × (5.3–)6–11(–15) mm, margins entire or erose-undulate, apex ± acute, rounded, or notched; stamens 26–64; filaments often connivent-connate in irregular clusters in proximal 0.5–4 mm, 1.8–8 mm, of unequal length, glabrous; anthers yellowish, 0.7–1.2 mm; styles 4, connate proximally, cylindric, 2.5–5.5(–7) mm, lobes sometimes connate proximally in pairs, 0.5–2.5 mm; stigmatic surfaces extending from adaxial lobes onto abaxial lobes and down to cylindric style. |
hypanthium sparsely to moderately strigose-sericeous or glabrous; sepals ovate-lanceolate, 2–3.5(–4.2) × 1.3–2.3 mm, apex acute to acuminate-caudate, abaxial surface sparsely to moderately strigose-sericeous or glabrous, adaxial surface glabrous except villous along distal margins; petals white, oblong-lanceolate to broadly oblong-ovate, (5–)7–8.5(–10) × 2.5–4.5(–5.8) mm; stamens 13–18(–24); filaments distinct, 1.3–4 mm; style 1, clavate, 2–3.2 mm, narrow base 0.5–1.5 mm; stigmatic portion 1.3–2 mm, distally lobed to 0.5 mm. |
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Capsules | oblong-globose or globose-turbinate, (3.6–)5–8(–9.5) × (3.5–)4–7(–9.5) mm, sepals persisting at equator or more distally, capsule distal surface often impressed in 4(–8) radiating lines. |
ovoid-turbinate, 3–5.5 × 3.2–5.5 mm, sepals ± persistent at distal 1/3 or more distally, capsule distal surface impressed in 4(–8) radial lines. |
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Seeds | short caudate distally, 1.5–2.5 mm. |
not caudate, 1–1.2 mm. |
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Philadelphus microphyllus |
Philadelphus mearnsii |
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Phenology | Flowering Apr–Jun; fruiting May–Nov. | |||||||||||||||||||||
Habitat | Limestone mountains, oak-pinyon zones. | |||||||||||||||||||||
Elevation | 1300–1800(–2200) m. (4300–5900(–7200) ft.) | |||||||||||||||||||||
Distribution |
AZ; CA; CO; NM; NV; TX; UT; WY; Mexico
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NM; TX; Mexico (Coahuila) |
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Discussion | Varieties 5 (4 in the flora). Within Philadelphus microphyllus as treated here, P. A. Rydberg (1905) recognized nine species, C. L. Hitchcock (1943) one species with eight subspecies, and Hu S. Y. (1954–1956) 11 species and four varieties, based on vestiture, leaf size and shape, and floral differences. Four varieties are recognized here within the flora area, with a fifth restricted to Mexico and without the needed varietal combination. Two characters are particularly important in distinguishing the varieties of Philadelphus microphyllus: adaxial leaf blade cuticle thickness and vestiture. Adaxial leaf blade cuticles can be thin and papillate, closely reflecting the adaxial epidermis cells (as seen at 30–40\x) or can be thick and smooth. Leaves with thin cuticles dry brown due to brownish granules developing in the epidermis; those with thick cuticles dry gray-green, olive green, or yellowish green without granules in the epidermis cells. Sometimes both types occur in a leaf in either a tight or bold mosaic pattern or the leaf blade may be papillate and brown only along its margins. Vestiture is mostly sericeous-strigose on leaves, stems, hypanthia, and sepals. The appressed hairs can be slender, short or long (0.2–1.5 mm), appressed, loosely appressed, ascending, or erect. The larger hairs have slender bases that allow them to be strictly appressed, but in some taxa, the base (upon drying) lifts and twists the hair upward, leaving the hairs oriented in many different directions; we refer to this condition as chaotic vestiture. In more densely vestitured plants, very slender, elongate, wavy-curved hairs form an understory beneath the more or less dense sericeous-strigose vestiture. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Philadelphus hitchcockianus, with its hypanthium and abaxial sepal surfaces glabrous, is here synonymized with P. mearnsii, which has its hypanthium and abaxial sepal surfaces moderately sericeous-strigose; substantial variation in this character is found in several populations. Hu S. Y. (1954–1956) alleged that P. hitchcockianus and P. mearnsii also differ in fruit size; however, that character is variable and overlapping. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 12, p. 479. | FNA vol. 12, p. 478. | ||||||||||||||||||||
Parent taxa | Hydrangeaceae > Philadelphus | Hydrangeaceae > Philadelphus | ||||||||||||||||||||
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Synonyms | P. hitchcockianus, P. mearnsii subsp. bifidus | |||||||||||||||||||||
Name authority | A. Gray: Mem. Amer. Acad. Arts, n. s. 4: 54. (1849) | W. H. Evans ex Rydberg: in N. L. Britton et al., N. Amer. Fl. 22: 174. (1905) | ||||||||||||||||||||
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