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Malacothamnus densiflorus


Higher Taxonomy
Family: MalvaceaeView DescriptionDichotomous Key
Common Name: MALLOW FAMILY
Habit: Annual to tree; generally with stellate hairs, often with bristles or peltate scales; juice generally mucilage-like; bark fibrous. Leaf: generally cauline, alternate, petioled, simple [palmate-compound], generally palmate-lobed and/or veined, generally toothed, evergreen or not; stipules persistent or not. Inflorescence: head, spike, raceme, or panicle, in panicle or not (a compound panicle), or flowers >= 1 in leaf axils, or flowers generally 1 opposite a leaf or on a spur; bracts leaf-like or not; bractlets 0 or on flowering stalks, often closely subtending calyx, generally in involucel. Flower: generally bisexual, radial; sepals 5, generally fused at base, abutting in bud, larger in fruit or not, nectaries as tufts of glandular hairs at base; petals (0)5, free from each other but generally fused at base to, falling with filament tube, clawed or not; stamens 5--many, filaments fused for most of length into tube around style, staminodes 5, alternate stamens, or generally 0; pistil 1, ovary superior, stalked or generally not, chambers generally >= 5, styles or style branches, stigmas generally 1 or 1--2 × chamber number. Fruit: loculicidal capsule, [berry], or 5--many, disk- or wedge-shaped segments (= mericarps).
Genera In Family: 266 genera, 4025 species: worldwide, especially warm regions; some cultivated (e.g., Abelmoschus okra; Alcea hollyhock; Gossypium cotton; Hibiscus hibiscus). Note: Recently treated to include Bombacaceae, Sterculiaceae, Tiliaceae. Mature fruit needed for identification; "outer edges" are surfaces between sides and back (abaxial surface) of segment. "Flower stalk" used instead of "pedicel," "peduncle," especially where both needed (i.e., when flowers both 1 in leaf axils and otherwise).
eFlora Treatment Author: Steven R. Hill, except as noted
Scientific Editor: Steven R. Hill, Thomas J. Rosatti.
Genus: MalacothamnusView DescriptionDichotomous Key


Common Name: BUSHMALLOW
Habit: Shrubs, sometimes spreading by rhizomes; sparsely to densely stellate-hairy and simple-glandular-hairy, flowers sometimes also with simple or 2-branched nonglandular hairs; stellate hairs stalked or not, 3--40-branched; glandular hairs not branched, often << stellate hairs. Stem: erect to ascending. Leaf: petioled; blades ovate to round (rarely diamond-shaped or +- reniform), unlobed or 3--7-palmate-lobed, margins generally toothed, bases cordate to truncate or wedge-shaped; stipules awl-shaped or linear to lanceolate or sometimes curved; transitioning in inflorescence into bracts +- resembling stipules. Inflorescence: Head-like to spike-like to panicle-like; bracts subtending the often highly reduced inflorescence internodes awl-shaped to linear to triangular to +- round, sometimes curved, occasionally 2--5-lobed, if 2-lobed resembling fused pair of +- modified stipules, smaller bracts sometimes deciduous; bractlets in whorl of 3 subtending calyx, distinct (occasionally fused at base in M. aboriginum), generally awl-shaped to linear, occasionally oblong or narrowly elliptic to ovate, green or partially to all red. Flower: calyx 5-lobed, not enlarging after flowering, not inflated, lobes triangular to ovate, tips acute to acuminate; petals exceeding calyx, unevenly obovate with rounded tip entire to notched or somewhat ragged-margined, pink to occasionally white and often varying in populations, generally drying closed after pollination or in some taxa drying partially to fully open; stamen tube +- included, filaments terminal and subterminal; ovary of 7--14 carpels, ovules 1 per cell, styles 7--14-branched, branches equal in number to carpels, stigmas head-like. Fruit: +- disk-like, fragile when dry, tip minutely stellate-hairy; segments 7--14, drying tan, 1-celled, wide-elliptic to obovoid-reniform, often notched near base, smooth-walled, fully dehiscent with each fruit segment splitting into two separate halves, beak 0. Chromosomes: 2n=34.
Etymology: (Greek: malakos, soft, thamnos, shrub) Note: Measurements for dry specimens; measurements for fresh specimens also provided in key. All Malacothamnus taxa can presumably hybridize; planting Malacothamnus taxa outside their natural range could threaten resident populations, a special concern for rare taxa. Hybridization/intergradation common where geographic ranges of some taxa meet; outside these zones of morphologically intermediate or intergrading plants, identification relatively simple and taxa relatively distinct. Such transition zones mostly between two taxa making parent taxa of intermediates easy to deduce; ranges of 3+ species abut near Santa Clarita making parentage of intermediate plants there unclear. Seeds generally germinate after fires in areas where woody plants burned; plants often short-lived, +- 5 years, but some may persist 20+ years post-burn.
eFlora Treatment Author: Keir Morse
Unabridged Reference: Morse 2023 Malacothamnus Volume 3 -- A Revised Treatment of the Genus Malacothamnus Based on Morphological and Phylogenetic Evidence https://doi.org/10.6084/m9.figshare.23937066
Malacothamnus densiflorus (S. Watson) Greene
NATIVE
Habit: <= 2.5 m, occasionally spreading by rhizomes. Stem: sparsely to moderately densely stellate-hairy, surface often visible through hairs without magnification, stellate hairs with branches <= 3.3 mm, mostly unstalked, stalks <= 0.4 mm, glandular hairs <= 1 mm (mean per plant < 0.1--0.7 mm). Leaf: blades +- round to widely ovate, length >= width, unlobed or obscurely to moderately 3--5-lobed, lobes rounded to acute, bases cordate to obtuse (truncate or obtuse), surfaces bright green adaxially, paler abaxially, stellate hairs with branches <= 1.3 mm, mostly unstalked, stalks <= 0.3 mm, abaxial stellate hair density 1--4(8.5) × adaxial, glandular hairs <= 1 mm. Inflorescence: spikes of interrupted dense flower clusters (very rarely some head-like or panicle-like in populations with mostly spikes); bracts subtending inflorescence internodes linear or awl-shaped to lanceolate or narrowly triangular, sometimes curved, occasionally shallowly to deeply 2--4-lobed; 3--15(19) mm, 0.5--3(6) mm wide, length 1--10(38) × width; bractlets subtending calyx linear, 5.5--16.5(18) mm, 0.2--1 mm wide, length 9--65× width, 0.5--1.5× calyx, green to partially red. Flower: calyx 8--16(18) mm, lobes 4--12 mm × 2--5 mm, lobe at base 2--4.5 mm wide, widest at base or <= 2.5 mm above base, length 1.3--3.8(4.5) × width, triangular to ovate, tip acuminate, abaxial calyx stellate hairs with branches 0.1--4.1 mm, mostly unstalked, stalks <= 0.3 mm, abaxial glandular hairs < 0.1--1.1 mm (mean per plant < 0.1--0.7 mm); corolla drying closed, petals to +- 2.5 cm.
Note: Varieties somewhat overlap geographically but easily distinguished by hair length and density, most definitively with microscopy. No clear intermediates between the varieties known but intermediates of var. densiflorus with other species may cause confusion. Var. viscidus tentatively recognized at the variety rank but further research may warrant its recognition at species rank.
Jepson eFlora Author: Keir Morse
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)

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Botanical illustration including Malacothamnus densiflorus

botanical illustration including Malacothamnus densiflorus

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Citation for this treatment: Keir Morse 2023, Malacothamnus densiflorus, in Jepson Flora Project (eds.) Jepson eFlora, Revision 12, https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=32516, accessed on April 19, 2024.

Citation for the whole project: Jepson Flora Project (eds.) 2024, Jepson eFlora, https://ucjeps.berkeley.edu/eflora/, accessed on April 19, 2024.

Malacothamnus densiflorus  
var. densiflorus
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©2016 Keir Morse
Malacothamnus densiflorus  
var. viscidus
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©2021 Keir Morse
Malacothamnus densiflorus-fasciculatus-intermediate
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©2023 Keir Morse
Malacothamnus densiflorus  
var. densiflorus
click for enlargement
©2016 Keir Morse
Malacothamnus densiflorus  
var. densiflorus
click for enlargement
©2019 Keir Morse

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Geographic subdivisions for Malacothamnus densiflorus:
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map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).





 

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