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Herbæ, frutices, rariusve arbores, mucilaginosæ, pube sæpissime stellata, foliis simplicibus alternis stipulatis: dicotyldoneæ, dichlamydeæ, hypogynæ, polyandri-monodelphæ, 5-polygynæ; calyce 5-sepalo æstivatione valvato; corolla 5-petala æstivatione convoluta, petalis basi cum imo tubo staminum connatis; antheris reniformibus unilocularibus; granulis pollinis hispidulis; seminibus amphitropis parce albuminosis; embyrone curvato, cotyledonibus foliaceis chrysaloideo-contortuplicatus.
MALVACEÆ, Juss. Gen. p. 271 (excl. § 5-7). R. Brown in Tuckey, Cong. p. 428. Kunth, Diss. Malv. p. 1. DC. Prodr. 1. p. 429. Endl. Gen. p. 978. Lindl. Veg. Kingd. p. 368.
THE MALLOW FAMILY belongs to a well-marked natural group (the Columniferæ of Linnæus), the plants of which agree in having the calyx valvate and the corolla convolute in æstivation; the stamens monadelphous in a column, or else more or less pentadelphous; the embryo large, with foliaceous cotyledons; and the leaves alternate and stipulate. The proper Mallow Family is readily distinguished from the other Columniferæ by its strictly monadelphous stamens, one-celled reniform anthers, and simple leaves.
This important, although not very large, family occurs in all parts of the world except the frigid zone. It is most copiously represented within the tropics and in the hotter parts of temperate regions, thence gradually diminishing in number towards the poles. There are more species in the northern than in the southern temperate zone [1]; and more in the New than in the Old World.
The Malvaceæ of temperate regions are nearly all herbs, one ornamental shrub, the Hibiscus Syriacus, forming the principal exception [2]; but within the tropics shrubby or even arborescent forms are common. Their pubescence is usually stellate, as shown in Plate 122, Fig. 1. The leaves are almost always petioled, usually palmately veined, and often lobed, but never truly compound. They are always furnished with a pair of stipules, which, however, are sometimes deciduous. The peduncles are axillary, and commonly articulated above the middle, or just beneath the flower. In many cases each flower is subtended by an involucel of three or several, or rarely one or two bractlets, forming what is usually denominated an exterior calyx [3]; the importance of which has been over-estimated in the systematic arrangement of the order.
The calyx and corolla are almost without exception pentamerous. The former is herbaceous and persistent, and the sepals, which are strictly valvate in the bud, are more or less united towards the base. The petals are commonly more or less oblique or inequilateral, as is usually the case when their æstivation is convolute. Their insertion is hypogynous; but their short claws are connate with the base of the stamineal column, which union also gives to the corolla the appearance of being slightly gamopetalous.
The explanation of this union is given by the investigations of M. Duchartre on the organogeny of the flower in Malvaceæa. He has shown that the petals and stamens (at least those which ordinarily appear in Malvaceæ) are identical in origin, both being developed from five original papillæ alternate with the calyx-segments and next within them, therefore morphologically representing the corolla. These, by parallel and collateral deduplication, give rise each to a petal and a cluster of stamens; and the union of these five clusters constitutes the stamineal column. This view is beautifully exemplified by the genus Sidalcea (Plate 120), recently proposed by myself,b in which the column is not resolved into simple filaments, but bears five petaloid lobes or phalanges of stamens, situated opposite the petals, into the base of which a vascular communication may be traced. That the anthers of each lobe are the result of the collateral deduplication of a single organ is evident on inspection of those cases in which the phalanges are two-cleft, and their divisions again two-forked, &c., until we reach the separate anthers; as in Plate 120. Fig. 9. Such stamens, perfectly resolved down to the column, compose the andrœcium of Modiola (Plate 128), in which the five component phalanges are more or less discernible, or Napæa (Plate 119), &c. The same, further multiplied by tranverse deduplication to form several series usually becoming free at more or less unequal heights, constitute, perhaps, the entire andrœcium of most other Malveæ. But what has become of the true stamineal verticil, the parts of which should alternate with the petals? M. Duchartre has detected this in the five lobes or teeth which terminate the naked apex of the column in such Malvaceæ as Pavonia, Hibiscus, Malvaviscus (Plate 131, Fig. 7), &c., and which, when the column is short, may be seen to alternate with the petals. This, again, is confirmed by Sidalcea, in which the column, prolonged above the sympetalous phalanges, terminates in antheriferous filaments, or in phalanges the principal, or five exterior, lobes of which apparently alternate with the phalanges of the outer column, and therefore with the petals themselves.
The anthers are reniform and one-celled by the confluence of the two lobes at their organic apex, as is shown by Plate 128, Fig. 3. The line of dehiscence is therefore transverse around the convex side, and the anther becomes two-valved. The cell of course exhibits, at an early stage, the septum which divides into two components the two loculi of the normal anther, the edge of which terminates in the line of dehiscence (Plate 117, Fig. 5). The grains of pollen are uniformly globose, and their coat minutely hispid; as in Plate 117, Fig. 6.
The flowers are hermaphrodite, except in the solitary case of Napæa (Plate 119), which is diœcious [4].
The pistils, from five (or very rarely fewer) to twenty of more in number, are more or less united in a ring around a central receptacle. The exception to this is in tribe Malopeæ [9], where the carpels are aggregated without apparent order into a head, is shown by Duchartre to arise from the ring becoming deeply five-lobed in the course of its development, the reentering angles being carried inwards and upwards so as to produce an apparent capitulum as the ovaries enlarge and accommodate themselves to the space.
The styles are usually combined at the base, or sometimes nearly to the summit. They correspond in number with the ovaries; except in Pavonia and its allies, where the branches of the style and the stigmas are twice as many as the ovaries or the cells of the compound ovary, — a character which defines a well-marked natural group, the tribe Ureneæ.
In the larger portion of the order, forming the tribe Malveæ as characterised in the following conspectus, the mature carpels separate from each other with more or less facility, and from the persistent central receptacle. A small portion of the surface of the inner angle or base of the carpel usually remains adherent to the receptacle, or to the base of the calyx. The stigmas are by all authors said to be capitate throughout the family; but this is not the case in what I have termed the Eumalveæ, which include all the European, and a considerable portion of the North American representatives of this tribe. In these, the styles, or their uncombined portions, are stigmatose throughout their whole length down the inner face, as in Caryophyllaceæ.
In the tribe Hibisceae, the carpels, usually of the same number as the petals, are strictly combined into a several-celled compound ovary, and the fruit is a proper loculicidal capsule, the valves being the dissepiments upon their middle, and commonly leaving no central axis.
The embryo nearly fills the seed, but is involved in a small quantity of mucilaginous, or at length fleshy albumen [5]. It is incurved or inflexed, and the broad and foliaceous cotyledons are more or less plaited together in the middle, and then infolded in the opposite direction, often enwrapping the base of the radicle.
The plants of the Mallow Family are uniformly destitute of noxious qualities [6], and nearly all of them yield a bland mucilage. On this account they are largely used as emollients and demulcents. The principal officinal plant for this purpose in Europe is the Marsh Mallow (Althæa officinalis): but the Okra or Gombo (Abelmoschus esculentus), a well-known ingredient of soups, &c., in warm climates, is still more mucilaginous. Nearly all Malvaceæ have a tough fibrous bark, which, in several plants of different parts of the world, is employed as a substitute for hemp. Of these the most important is Hibiscus cannabinus, which produced the Sun-hemp [7] of India. But far the most important product of the family is cotton, which consists of the long hairs that cover the seeds in the genus Gossypium; a tropical genus of great ambiguity as to the number of species, but which was originally given to both the New and to the Old World.
Into the subjoined arrangement I have introduced all [8] the admitted genera of the order. Several of them are known to me only by the published characters.
CONSPECTUS OF THE TRIBES AND GENERA
a In Annales des Sciences Naturelles, 3eme ser.
4. p. 123.
b Plantae Fendlerianæ, p. 18.
c Although in the generic characters the stigmas are said to be
“capitellate,” it is evident from the figures that they are just as
in Malva.
d Mr. Bentham mentions a Texan species [30]; but
none has fallen under my observation.
[1] There may be more species in the southern temperate
zone than the northern; Argentina alone has more species than the whole of
Europe.
[2] There are other shrubby or arborescent temperate taxa,
e.g. the genera Hoheria and Plagianthus in New Zealand, and the
genus Corynabutilon in temperate South America.
[3] Now known as an epicalyx.
[4] The Australian Gynatrix is also dioecious. Even in
North America some species of Callirhoe are gynodioecious.
[5] Some basal genera, including Radyera and
Lagunaria, are exceptions to this rule.
[6] The Malvaceae are not all wholly innocuous: inter
alia, Gossypium and allies produce a class of toxic compounds known
as gossypols; nitrate toxicosis has been recorded as a result of
ingestion of Malva species; and dermatitis can be caused by the hairs of
some species.
[7] Now better known as kenaf.
[8] The number of known genera has increased severalfold, due
both to changes in circumscription of genera, and to the description of new
taxa. Newer North American genera include Eremalche, Iliamna,
Malacothamnus and Malvella.
[9] Malopeae is no longer accepted as a tribe. Malope
and Kitaibelia are both shown by DNA evidence to fall within Malveae,
and morphology suggests that they are sister taxa. There is no DNA evidence for
the position of Palaua, but I suspect that it is related to other South
American members of Malveae, and the similarity of fruit morphology to that of
Malope and Kitaibelia is a homoplasy.
[10] Also found in Anatolia.
[11] Currently spelt as Palaua.
[12] The internal divisions of Malveae are unclear, but
current opinion holds to 2 subtribes - Malvinae and Abutilinae.
Malvastrum, Sphaeralcea and Modiola belong in Malvinae,
whilst the remainder of Sideae and Abutileae compose Abutilinae.
[13] Lavatera (also Saviniona and
Navaea) regularly has a 3-part epicalyx.
[14] Alcea (Hollyhocks) is now separated from
Althaea (Marshmallows).
[15] There is also a species, Althaea ludwigii, from
Africa.
[16] Lavatera extends to North Africa, and into Asia.
There are also species usually classified in this genus in Australia and
California, but these may be more appropriately placed in Malva.
[17] Saviniona is sunk in either Lavatera or
Malva, depending on treatment.
[18] Navaea is usually sunk in Lavatera, but
there is a case for recognising it.
[19] Now sunk in Sphaeralcea.
[20] This tribe is currently known as Malvavisceae.
[21] Now divided into two tribes, Hibisceae and Gossypieae.
[22] Also present in South East Asia, southern China and
Australia.
[23] Currently known as Senra.
[24] Currently known as Cienfuegosia
[25] Also present in tropical Africa.
[26] Also present in the Americas and Australia.
[27] Lagunaria has an impersistent involucel.
[28] Also native to Queensland.
[29] Sunk in Hibiscus.
[30] The Texan species is Cienfuegosia drummondii.
[31] The currently accepted spelling is Callirhoe.
(Gray) Lewt.
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