mallows

genus Malva

Member of mallow family (family Malvaceae)
dicots (class Magnoliopsida)
flowering plants (subphylum Angiospermae)

There are no other wild species of this genus in California.

Mallows have an extra epicalyx cupping the calyx. (Jepson calls it an involucel with bractlets.)

Key features:

are epicalyx segments fused to each other at the base?
are epicalyx segments partially fused to the calyx beneath?
peel back the calyx segments to view the fruit within.

There is a very good guide to the wild mallows of New Zealand that conveniently encompasses all Bay Area mallows. Valerio Lazzeri also has a key to selected mallows.

epicalyx segments are fused to each other (at the base)

island mallow
Malva assurgentiflora

shrub

all others are an herb or subshrub

petals 25–45 mm
leaf has distinctive triangular lobes with triangular teeth

tree mallow
Malva arborea

petals 15–20 mm with 5 dark veins

petals are dark at the base

calyx ± 4 mm
epicalyx free parts ± 8 mm long, > calyx

cretan mallow
Malva multiflora

petals 10–16 mm, generally with 3 dark veins

petals are not dark at the base

calyx ± 4 mm
epicalyx < calyx
fruit is smooth with longitudinal grooves

epicalyx segments are partially fused to calyx, separate from each other

bull mallow
Malva nicaeensis

petals 5–12 mm, veins generally dark
sepals 4–6 mm
epicalyx segments widely lanceolate to ovate, relatively broad and close to each other, bases fused to calyx
fruit is reticulated
stem densely hairy, usually erect but may be matted down (e.g. if squashed on a road)

epicalyx segments are free

common mallow
Malva sylvestris

petals generally 15–30 mm, veins dark

all others in this section have shorter petals

sepals 6–8 mm
epicalyx segments 3–7 mm long, 2–4 mm wide, free
fruit is reticulated

dwarf mallow
Malva neglecta

petals generally twice as long as sepals (8–12 mm)
sepals 4–6 mm
epicalyx segments widely linear to narrowly lanceolate, narrow and distant from each other, bases free from each other and from calyx
fruit is smoothly ribbed
stem densely hairy

photo

cheeseweed mallow
Malva parviflora

petals 3–5 mm
sepals ~3 mm
epicalyx segments 1–2 mm long, linear to thread-like
fruit is reticulated and always exposed by the calyx
stem slightly rough or hairy, usually prostrate or decumbent

4 observed taxons / 3 unobserved taxons / 1 key

Chris’s observations: 15 (13 are research grade)

Locations:

Bay Trail: 2
Coyote Lake / Harvey Bear Ranch CP: 2
Alum Rock Park, San Jose
Coyote Hills RP
Ed R. Levin CP
Garin RP
La Honda Creek OSP
Mission Peak RP
Purisima Creek Redwoods OSP
Russian Ridge OSP
Santa Teresa CP
Skyline Ridge OSP
Ulistac Natural Area, Santa Clara

Months:

Jan.: 2
Feb.: 1
Mar.: 0
Apr.: 4
May: 1
Jun.: 6
Jul.: 1

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Taxon info: iNaturalist – Calflora – Jepson eFlora – FNA

Bay Area species: iNaturalist – Calflora