Part 51

The best-known genus is Musa, the Banana (Fig. 314). From the short rhizome arise enormously large, spirally-placed leaves, whose sheaths envelope one another, and form an apparently aerial stem, several metres in height. The inflorescence is a terminal spike with floral-leaves placed spirally, and sometimes magnificently coloured; in the axils of each of these several flowers are situated in two transverse rows (accessory buds); the lowest flowers in the inflorescence are ♀, the central ones ☿, the upper ones ♂, so that fruits are only found in the lower region of the inflorescence, the remaining portion persisting as a naked axis after the floral-leaves and flowers have fallen off; the inflorescence terminates in an ovoid bud formed by the flowers which have not yet opened (Fig. 314, the left-hand figure). The perianth-leaves are united (except the posterior one). The fruit (known as a “Banana”) is a berry, having the form of a smooth, short, three-cornered Cucumber (as much as 30 cm. in length); inside the tough skin is found a farinaceous, aromatic pulp. No seed is developed in the cultivated species.--~Several Musa-species are cultivated in the Tropics for the sake of the fruit (M. paradisiaca, M. sapientum); for the fibrovascular bundles, M. textilis (Manilla Hemp).--Their home is, no doubt, the Tropics of the Old World; they were introduced into America before the arrival of Europeans. Musa ensete has dry, leathery fruits; an ornamental plant.~

In Musa the barren, posterior stamen belongs to the inner whorl; and also in Strelitzia and Ravenala; the latter may have all 6 stamens developed. In Heliconia, on the contrary, it belongs to the outer whorl; in Heliconia the perianth-leaves are differently arranged, and there is only one ovule in each loculus. The three latter genera have dry fruits and leaves arranged in two rows. In the “Travellers’ Palm” (Ravenala madagascariensis) the foliage-leaves form an enormous fan.--Tropical; about 50 species.

The order may be divided as follows:--1. Museæ: Musa, Ravenala, Strelitzia in the Old World. 2. Heliconiæ: Heliconia in the New World.

Order 2. =Zingiberaceæ.= Perianth most frequently divided into calyx and corolla. Calyx gamosepalous. Only 1 fertile stamen (the posterior, Fig. 315, belonging to the inner whorl) with quadrilocular anther, which encloses the style in a furrow; the 2 stamens in the outer whorl are staminodes, the median one (the anterior) is wanting. The 2 lateral staminodes of the inner whorl form the “labellum” (Fig. 315 lab), which usually is the largest segment of the flower, and is often bilobed. Ovules many. The fruit in some is a leathery, 3-valved capsule, with loculicidal dehiscence; in others it is more or less berry-like and indehiscent, or irregularly dehiscent. Straight embryo.--The aerial stem is seldom developed to any extent, and the inflorescences, which are (compound) spikes or racemes, often with coloured floral-leaves, spring in some (e.g. Zingiber officinale) directly from the rhizome. The leaves are arranged in two rows.--The ovary in a few instances (Globba and others) is unilocular, with 3 parietal placentæ.

They are perennial herbs with fleshy and tuberous rhizomes, which are used as condiments and in medicine on account of their pungent and aromatic properties and also for starch, dyes, etc. OFFICINAL: rhizomes of Zingiber officinale (Ginger, unknown wild, but cultivated generally in the Tropics), of Curcuma longa (Turmeric, a dye, E. India) and C. zedoaria, of C. angustifolia and others (as E. India Arrowroot), of Alpinia officinarum, China (galangal). “Preserved Ginger” from Alpinia galanga. Similar aromatic materials (volatile oils) are present also, for example, in the fruits; Cardamom fruits and seeds (from Elettaria cardamomum, China, seldom from E. major).

315 species; Tropics, preponderating in the Eastern Hemisphere, India, and especially S. Asia, whence all the aromatic species originate; they are now commonly cultivated in the Tropics. Some are ornamental plants in greenhouses, e.g. Hedychium, Costus, etc. Globba (with axillary buds in the inflorescence, as in Ficaria), Renealmia, Kæmpferia.

Order 3. =Cannaceæ.= American herbs without aromatic properties. Flowers asymmetric (Fig. 316). Calyx polysepalous. The stamens are petaloid (Fig. 316 st) and barren with the exception of one (the posterior), which bears on one of its edges a bilocular anther; another, which is especially large and coloured, is termed the labellum. The style is compressed and leaf-like, with a small stigma at the apex. Ovules numerous in the 3 loculi. The capsule is furnished with warts or soft prickles. Embryo straight.

Canna (30 species; Trop. Am.). The inflorescence is a terminal spike with 2-flowered unipared scorpioid cymes in the axils of the floral-leaves. Ornamental plants: Canna indica, etc.

The diagram of the andrœcium of the Cannaceæ and Marantaceæ may be represented in the following manner (calyx, corolla and gynœceum being omitted):--

CANNACEÆ. MARANTACEÆ.

w w w w st st w lab wi c * *

w The lateral staminodes, “wings;” st fertile stamen; * the suppressed stamen; lab labellum; c hood; wi inner-wing.

The labellum of the Cannaceæ corresponds with the hood of the Marantaceæ and not with the labellum of the Zingiberaceæ.

Order 4. =Marantaceæ.= The flower is asymmetrical. Only 1 or 2 of the 3 stamens in the outer whorl are present as staminodes; in the inner whorl 2 are petaloid and of the sixth stamen one-half is developed as a staminode and the other half bears a bilocular anther. One ovule only in each loculus. The style is strongly curved and at first enclosed in one of the staminodes (hood) of the inner whorl; later on it springs elastically forward towards the other staminode (inner-wing) of the same whorl. The stigma is very oblique or 2-lipped. Two of the three loculi of the ovary, in some (Maranta, Thalia) become small and empty. Embryo curved. Leaves in two rows, with sheath, stalk, and blade (Fig. 317); at the base of the last is a characteristic swelling (articulus).--~Phrynium, Calathea, Stromanthe, Ctenanthe, Saranthe, etc. About 150 species; tropical, especially America. The starch of the rhizome of Maranta arundinacea is OFFICINAL, “West Indian Arrowroot.”~

Family 7. =Gynandræ.=

The flowers are hermaphrodite and constructed on the ordinary 3-merous, pentacyclic type with petaloid, epigynous, strongly zygomorphic perianth, and generally one-stamened by the suppression of the other 5 stamens. The family has derived its name from the fact that the stamen is united with the style into a “stylar column” (except Burmanniaceæ). All are herbs; many grow as epiphytes on other plants.

This family and the Scitamineæ occupy correspondingly high positions among the Monocotyledons; these two families may therefore be placed close together, although one cannot be derived from the other. The first of the two orders is very small, but the second is very rich in species. The Apostasieæ are best classed with the Orchidaceæ and have no independent place.

Order 1. =Burmanniaceæ.= This order forms a transitional link between the Gynandræ and the epigynous Liliifloræ (Amaryllidaceæ), in having a 6-leaved perianth, and 6–8 stamens; but some have a labiate perianth (the median perianth-leaf of the outer whorl being very large). The ovary is most frequently unilocular with three parietal placentæ; but in some it is 3-locular with axile placentation. Capsule. Seeds ∞, small, with endosperm. The relationship to the Orchidaceæ is shown especially in the very imperfectly developed embryo and in the ovary. Small, tropical herbs (59 species); some are saprophytes.

Order 2. =Orchidaceæ.= The epigynous, petaloid perianth is strongly zygomorphic in having the posterior leaf of the interior whorl, the lip (labellum), differing from all the other leaves in form, size, and colour (except Apostasieæ); the position of the labellum is very frequently reversed, being turned forwards and downwards by the twisting of the ovary (Fig. 318 A). Only 1 of the stamens--the anterior of the external whorl--is developed and bears an anther (by the twisting of the ovary it is turned posteriorly and upwards); the others are entirely wanting (indicated by * in Fig. 318 A) or present as staminodes (Fig. 318 A, δ δ) (except Apostasieæ, Cypripedileæ); the filaments are united with the style to form a column (Fig. 318 B), the stylar-column (gynostemium), and the anther (a) is thus placed on its apex and exactly behind or over the stigma (s). The anther is 4-locular; the pollen-grains do not separate (except Apostasieæ, Cypripedileæ) but remain united either in tetrads or in masses, which correspond to a pollen-mother-cell (Fig. 320 C, D, E); or the pollen-grains, formed in each of the two anther-halves, remain united and form one or a few wax-like masses (pollen-masses, pollinia). The 3 carpels form a unilocular ovary with 3 parietal, deeply bifid placentæ (except Apostasieæ, Selenipedilum). Only the two lateral carpels are prolonged and developed into the stigma (Fig. 318 B, s), while the one lying in the median line, which is situated just within the anther (Fig. 318 A), becomes either rudimentary or developed into the “rostellum” (“a small beak”), on which the sticky bodies (glandulæ) arise; by aid of these the heavy, connected pollen-masses may be glued to the insects which visit the flower, and pollination is thus secured (in Apostasieæ and Cypripedileæ the 3 carpels each contribute to the formation of the stigma). The fruit is a capsule which most often dehisces by 6 valves, 3 of which are broader and bear the placentæ, and 3 alternating with them are narrower and barren (except Vanilla). The very numerous and exceedingly small seeds have no endosperm, and have a somewhat spherical embryo without any trace of external organs. The testa is membranous and loose.

The Orchids are all perennial herbs with diverse habits and varying morphological structure (see the genera); the leaves are scattered, of the usual Liliaceous form, and the inflorescences in all cases are racemes or spikes (sometimes branched), with subtending bracts, but without bracteoles.

The forms which are the least modified are described first.

=1.= APOSTASIEÆ. The perianth-leaves are almost alike and free. The column is straight, with 3 equally-developed stigmas. Neuwiedia has 3 perfect stamens (1 median of the outer whorl, and 2 lateral of the inner whorl); Apostasia has only 2 perfect (inner lateral) and one barren (the median of the outer whorl), which however may be entirely wanting. The 3 posterior stamens are entirely suppressed. The pollen is powdery. The ovary is 3-locular with axile placenta. 7 species (Tropical East India, Australia).

=2.= CYPRIPEDILEÆ. The flower is strongly zygomorphic with a large boat-shaped labellum. There are two perfect stamens belonging to the inner whorl, and the median anterior (later on the posterior) stamen of the outer whorl is transformed into a large, barren, shield-shaped body (Fig. 319). Selenipedilum has a 3-locular ovary, but Cypripedilum (Ladies’-slipper) has a unilocular ovary with 3 parietal placentæ--the typical structure for the Orchids. The pollen-grains are separate (not in tetrads) and all the 3 lobes of the stigma are constructed to receive them. This group is therefore, next to the Apostasieæ, the least modified among the Orchids; in all the following groups, one of the lobes of the stigma is differently developed from the others, and there is only one stamen.--Terrestial Orchids.--~The pollination of C. calceolus is effected by the forcible entrance of insects into the boat-shaped labellum (Fig. 319 p’) at i, and their escape at ex (in 2) where the anthers are situated; in this way the stigmas will first be touched and then the anthers. The pollen-grains are surrounded by a sticky mass in order that they may adhere to the insects.~

=3.= NEOTTIEÆ. The majority are terrestrial Orchids with creeping, sympodial rhizomes; the blades of the leaves are not detached from the stem at joints, and have convolute vernation. The anthers do not drop off, but persist in the withered condition; their apex is brought in contact with the rostellum (acrotonous Orchids). The pollen-grains are united in tetrads, which, however, often hang loosely together in pollinia, attached to a sticky part of the rostellum (“adhesive disc”), so that they adhere to the insects, and are by them transferred to the stigmas. Spiranthes. Listera; Neottia. ~N. nidus-avis (Bird’s-nest) is brown (it has little chlorophyll) in colour, has no foliage-leaves, and lives mainly as a saprophyte; the rhizome is studded with unbranched, fleshy roots which may form buds at their extremities.~--Vanilla climbs by aerial roots. The fruit is fleshy and hardly opens, or does so irregularly.--Epipactis, Cephalanthera.--Epipogon and Limodorum are saprophytes without chlorophyll.

=4.= OPHRYDEÆ. Anthers 2-locular, not falling off, on a very short column. The anther is united at its base with the rostellum (basitonous Orchids, Fig. 320 A, B), while in all other Orchids it is connected at the apex (acrotonous Orchids). The pollen-grains in each loculus are united into small “masses” (massulæ), each of which corresponds to a pollen-mother-cell in the anther, and which hang together by elastic threads (Fig. 320 C, E). Each pollinium is attached at the base by a stalk (caudicle) to an adhesive disc, formed by the modified stigma (rostellum), and is easily liberated from it (Fig. 320 C, D, F). The pollinium, which is formed in an anther-loculus, together with its caudicle and adhesive disc, is termed “pollinarium” (Fig. 320 C).--All Ophrydeæ are terrestrial with tuberous roots, two of which are present in the flowering period, an older one (from the preceding year) containing the nourishment for the flowering-shoot of the year, and a young one which is intended to contain the reserve material for the following year. Inflorescence terminal.

Orchis. The lip has a spur; each of the club-like pollinia is attached to its own adhesive disc, the discs being enclosed in a common pouch formed by the rostellum (Fig. 320 C, D). ~Tubers ovate, undivided: O. morio, mascula; tubers palmate: O. incarnata, maculata, majalis.~--Ophrys; no spur, the two adhesive discs are each enclosed in a separate pouch (Fig. 320 F).--Anacamptis and Serapias have one adhesive disc.--Habenaria, Gymnadenia, Platanthera, Herminium, Nigritella, Cœloglossum, etc., have naked adhesive discs (no rostellum).

=5.= EPIDENDREÆ. Acrotonous Orchids with deciduous anthers (except Malaxis); 2-8 wax-like pollinia, with or without caudicles; generally no adhesive discs. Malaxis (the flower is twisted through a complete circle, causing the labellum to be turned upwards), Sturmia and Corallorhiza (Coral-root); the latter has a creeping, coral-like rhizome without roots, and is destitute of chlorophyll except in the ovary. The other two somewhat resemble the tropical Orchids in having the lower internodes of the axis of the inflorescence tuberous. Liparis; Calypso. Most of the genera are tropical epiphytes and many have aerial, green tubers formed from one or more stem-internodes; Dendrobium, Eria, Phaius, Bletia, Epidendrum, Cattleya, Lælia, Pleurothallis, Restrepia, Masdevallia, Bulbophyllum, etc.

=6.= VANDEÆ. These resemble the preceding but have only 2 wax-like pollinia in each anther, which are attached by a caudicle to the adhesive disc of the rostellum. Nearly all are tropical epiphytes. Stanhopea, Catasetum, Maxillaria, Oncidium, Vanda, Polystachya, etc.