Kingdom: Plantae
(Unranked): Angiosperms
(Unranked): Eudicots
(Unranked): Rosids
Order: Malvales
Family: Malvaceae
Genus: Sylvestris
Species: M. sylvestris
Binomial name: Malva sylvestris 
Common name: Common Mallow, Purple Mallow, Cheeses, Large-flowered mallow, Zebrina mallow.

Malva sylvestris is a perennial ascending to erect herb from Western Europe, North Africa and Asia and is now naturalised in New Zealand. It grows to a height of 1 m and grows freely in fields, roadsides and on wasteland. Its flowers are a bright mauve-purple, with dark veins.\
The description below is from Webb et al. (1988) Flora of New Zealand. Volume 4.]
Perennial, ascending to an erect herb. Stems glabrous to densely hairy with simple and stellate hairs. Lvs ± glabrous to densely hairy, reniform to suborbicular, obtuse to cordate at base, shallowly or moderately 3-5-(7)-palmately lobed and crenate, 1-15-(20) cm diam.; petioles 1-15-(30) cm long; stipules narrowly to broadly ovate with acute apex, 3-10 mm long. Fls 2-10 in axillary clusters or irregular racemes; fruiting pedicels 10-45 mm long; epicalyx segments narrow-oblong to elliptic-ovate, somewhat <calyx; calyx teeth broadly ovate with acute apex, sparsely to densely hairy with stellate or simple hairs and ciliate, not enlarged at fruiting; petals from deep pink to reddish or bluish purple with darker markings, 2-5× as long as calyx, 12-30 mm long. Mericarps 8-12-(15) per fr., usually glabrous, strongly reticulated veined on back; edges sharply angled but not winged.

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Malva sylvestris has various leaf shapes. The photo below is of a round shape. See the different shape of  the leaves in the photo above

A newly formed seed capsule
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A dried seed capsule.
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Thanks to Wikipedia for text and information:

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