Deciduous trees. Leaves alternate, simple, mostly broadly ovate, cordate-based and serrate, petiolate, with stipules falling early. Inflorescence a cyme, with 2–25 fragrant flowers whose peduncle is fused to a persistent papery bract which is dispersed with the fruits; flowers actinomorphic, bisexual, hypogynous. Sepals 5, free. Petals 5, free, usually creamish-yellow. Stamens numerous, more or less coherent in 5 bundles. Style 1; stigma capitate, more or less lobed. Ovary 5-celled; each cell with 2 ovules. Fruit a nut, with 1–3 seeds.

Contains about 35 genera and about 300 species, widely distributed from temperate to tropical regions.

Tilia

Deciduous trees with a strong tendency to sprout from the base. Leaves alternate, often ovate-cordate and asymmetrical, with a slender petiole; stipules present, falling shortly after the leaves expand. Inflorescence with peduncle fused to the upper surface of an elliptical or oblanceolate bract; flowers in a dichasial cyme, strongly scented, entomophilous. Sepals 5, boat-shaped, with hair-covered nectaries on their upper surfaces. Petals 5, strap-shaped, cream to bright yellow. Stamens numerous, in 5 bundles; petal-like staminodes may be present. Ovary spherical, with 5 cells, each containing 2 ovules. Style 1, slender; stigma small, 5-lobed. Fruit a nut, usually indehiscent and containing 1–3 seeds. The fruits are shed with the bract attached and acting as a wing.

Contains about 30 species in the temperate regions of the northern hemisphere. When taxa come together in cultivation they tend to hybridise.

Perennial herbs. Basal leaves forming tubular pitchers with a small lamina at the top. Inflorescence a single terminal flower; flowers bisexual, actinomorphic, nodding. Sepals 5, more or less petaloid, with 3 small bracteoles resembling an epicalyx. Petals 5, showy. Stamens numerous. Style 1, short; stigma greatly expanded, peltate. Ovary 5-celled, with many ovules in each cell. Fruit a capsule.

Contains 3 genera and about 17 species in Atlantic North America, California and the Pakaraima Mountains in the Guiana Highlands.

Sarracenia L.

As family.

Ten species in Atlantic North America, some widely cultivated and not infrequently naturalised. Hybrids are of frequent occurrence.

McDaniel, S. (1971). The genus Sarracenia (Sarraceniaceae). Bull. Tall Timbers Research Station 9 : 1–36.

Deciduous, monoecious trees. Leaves alternate, simple, palmately lobed, petiolate, with stipules when young. Flowers hypogynous, actinomorphic, in dense spherical unisexual clusters, two to several clusters on a pendulous peduncle, forming a usually unisexual inflorescence. Perianth small, fused or not, of 1–2 whorls of usually 3–4 segments. Male flowers with 3–4 stamens. Female flowers usually with 3–4 staminodes and 5–8 free carpels, each with 1(–2) ovules. Styles 1; stigma linear. Fruit an achene with long hairs at base.

Contains one genus with about 10 species in south-east Europe, south-west Asia and North America.

Platanus L.

Like family.

Contains about 10 species in south-east Europe, southwest Asia and North America.

Perennial insectivorous herbs. Leaves all in basal rosettes, reddish and covered with sticky glandular hairs, petiolate, with stipules. Inflorescence a simple cyme on a peduncle from ground level; flowers bisexual, actinomorphic, hypogynous, usually remaining closed. Calyx 5- to 8-lobed. Petals 5–8, white. Stamens 5–8. Styles 2–6, often deeply divided above and free or fused below; stigmas linear. Ovary 1-celled, with many ovules. Fruit a capsule.

Contains 4 genera found throughout the world but concentrated in Australia and New Zealand.

Sundews entrap insects, which are caught on the sticky glandular hairs of the outer edge of the leaves. The leaf then coils over the insect and uses the shorter glandular hairs on the centre of the leaf to digest it.

Drosera L.

As family.

Contains about 100 species in acid, sandy, stony and boggy places.

Annual or perennial, usually glabrous herbs. Stems 5-angled, usually brittle, sometimes climbing; juice watery. Leaves usually alternate, very rarely opposite, ternately or pinnately divided, triangular to ovate in outline, rarely with leaflets decreasing in size towards the base, without stipules. Flowers usually strongly zygomorphic, sometimes more regular, bisexual, hypogynous. Sepals 2, small, petaloid, usually somewhat peltate and lateral, not covering the petals in bud, more or less caducous. Petals 4, in two dissimilar pairs; outer coherent at apex in bud, later free, fused to the androecium and the inner petals at the base, winged towards the apex, sometimes with a median crest, one or both spurred or saccate; inner narrower, coherent at apex, jointed and flexible at the middle, enclosing the androecium and gynoecium, with a median wing on the distal part and two lateral wings abaxially. Stamens 2, tripartite, the central branch bearing a two-celled anther, the lateral branches each bearing a one-celled anther, nectariferous at base; anthers rounded-elliptical, closely adhering to the stigma. Stigma usually flattened. Pollen grains spherical, pantoporate or colpate. Fruit a capsule or achene. Seeds with a small embryo and copious endosperm.

The Fumariaceae are often united with the Papaveraceae, but the markedly zygomorphic flowers of the majority of the species, which make it an easily recognisable group, suggest that they are most usefully treated as a distinct family. There are 17 genera and between 360 and 420 species, arranged in two subfamilies, one of which is not represented in this flora. Native of the north temperate zone and South and East Africa, but introduced as garden plants and weeds in many other parts of the world. The family is here arranged according to the system of M. Lidén (1986).

Small to moderate-sized epiphytes or terrestrial herbs. Rhizome long creeping, densely covered with scales. Fronds usually borne in 2 rows; lamina simple to pinnatifid. Sporangia borne in small discrete sori terminal on the veins. Spores monolete.

Contains 11 genera and about 150 species, mostly in the Old World tropics or subtropics.

Davallia Sm.

Perennial herbs with polystelic rhizomes, broad dorsal and ventral meristeles and clathrate scales. Fronds distant, in 2 ranks, articulated to rhizome; lamina 3- to 4-pinnate; stipe with several vascular strands, jointed to the rhizome. Sori submarginate. Indusia elongate, vase-shaped, opening near the margin. Spores bilateral.

Contains about 40 species, mostly from the warm temperate or tropical Old World. D. bullata Wall. agg. has been recorded as a greenhouse escape.

1. D. canariensis (L.) Sm. Hare's-foot Fern Trichomanes canariensis L.; Polypodium lusitanicum L.

Perennial herb with a rhizome 1.0–1.5 cm thick which is densely silky-scaly. Fronds up to 80 cm, with stipe half as long as lamina; lamina 4-pinnate, with the ultimate segments lanceolate to ovate-oblong, mostly bidentate. Sori on underside of lamina, submarginal. Indusia elongate, vase-shaped, attached at base and sides and opening towards margin of lamina. Spores bilateral.

Introduced. Formerly naturalised on a wall at Coin Colin, St Martin, in Guernsey. Native of south-west Europe and Macaronesia.

Monoecious trees or shrubs. Leaves alternate or clustered in false whorls; stipules large and deciduous. Flowers generally solitary, bisexual, hypogynous, often with elongate receptacle. Perianth segments 6–18, often all petaloid. Stamens numerous, free, spirally arranged. Fruit a follicle or indehiscent and berry-like; seeds mostly large.

Contains 12 genera and some 220 species.

Usually evergreen, occasionally deciduous trees and shrubs. Trunk usually freely branched. Leaves simple, usually narrow. Male sporangia borne on sporophylls arranged in strobili. Female sporangia borne in naked ovules, either singly and terminally or borne on scales in female strobili, the fertilised ovule being retained on the sporophyte until ripe.

The Pinophyta, commonly known as conifers or firtrees, are woody, usually evergreen trees and shrubs with secondary thickening and xylem without vessels. The relatively large development of the trunk as compared with that of the branches is characteristic of many species. The mature wood is distinguished from that of the flowering plant trees by the absence of vessels and is composed of tracheids or elongated spindle-shaped cells with closed ends, which are dove-tailed between one another. They have woody walls marked with bordered pits. The medullary rays traversing the wood are usually only one cell thick and rarely visible without magnification. In some genera resin ducts are conspicuous as small spots on the transverse surface of the wood. Heartwood and sapwood are not always easily distinguished. The branches are verticillate, usually patent, and often gradually get smaller upwards, thus producing a conical outline to the tree. As it gets older the tree often loses its lower branches and the branches of the apex become less regular. Whether the ends of the branches are erect, ascending, upswept, spreading, drooping, sloping down or hanging is often characteristic of the species and can make identification possible at a distance. The above adjectives seem more appropriate than any technical terms. The young shoots vary greatly in colour and degree of hairiness in the different species and are usually markedly different from the older twigs.

The buds are like those of flowering plant trees. The leading shoot often has a terminal bud surrounded by smaller buds; in lateral shoots the terminal bud is often accompanied by two smaller buds, which sometimes remain dormant. The colour and shape of the bud-scales and whether they secrete resin or not are often good specific characters.

Herbs, shrubs or climbers, rarely trees. Leaves usually alternate and usually with sheathing stipules (ochreae). Flowers bisexual or unisexual. Perianth segments 3–6, sepaloid or petaloid, free or connate, persistent, imbricate in bud. Stamens usually 6–9; anthers 2-celled, opening lengthways. Ovary superior, syncarpous, unilocular, with a solitary basal orthotropous ovule. Fruits indehiscent, hard, trigonous or lenticular, usually enveloped in the perianth.

Contains about 40 or more genera and 800 species throughout the world, but mainly in temperate regions.

There has been much dispute over how many genera there are in the Polygonaceae. Our examination of the details of the flowers has shown that there is so much variation in size and shape, even on the same plant, that they cannot be used to any extent in this classification. On the other hand an examination on an almost daily basis over the last few years of many species in Cambridge Botanic Garden has shown that the type of inflorescence and general habit divides them into a number of natural groups. Either the whole lot except Rumex and related genera can be put in one genus, Polygonum, or each of these groups can be regarded as a distinct genus. Any intermediate position, which is what has mostly been adopted, brings about problems with intermediates and the use of keys. Believing that the general tendency is to split, we have followed the latter course. Galasso et al. (2009) agree with some of our decisions.

In the case of species the same principles have been applied and we have split rather than lumped. Selfpollination appears to be widespread, but when hybrids do occur they are often perennials and spread vegetatively. In the genus Polygonum sensu stricto we have followed the principles of Alexis Jordan, who grew these plants for many years; those that we have grown support his findings. Arthur Chater has collected these plants extensively in Cardiganshire and has found almost exactly the same number of taxa as we have found around Cambridge. Rumex is completely different and all taxa appear to hybridise with one another, except those that we have removed to Acetosella and Acetosa.

Perennial, aquatic herbs. Leaves mostly submerged and opposite, deeply and finely palmately dissected, petiolate; floating leaves alternate, peltate, entire, without stipules. Flowers solitary in leaf axils, slightly emergent, bisexual, actinomorphic, hypogynous; pedicel long. Perianth segments 6, free, white, in 2 whorls. Stamens 6. Styles 2–4, short; stigma capitate. Fruit an indehiscent usually 3-seeded follicle.

Consists of 2 genera and 7 species

Herbs. Stems simple or sparingly branched, bearing roots. Leaves simple, with 1 vein. Sporangia homosporous or heterosporous, borne singly in leaf axils or on the upper side of a leaf near the base; sporangium-bearing leaves often aggregated into a cone. Gametophytes of homosporous species free-living, subterranean, mycorrhizal and saprophytic, those of heterosporous species much reduced and retained in the spore, which lies on the ground.

Contains 3 isolated families worldwide, each in a separate order.

Monoecious trees. Leaves alternate, simple, serrate, usually asymmetrical at base, petiolate, with stipules when young. Flowers produced before the leaves in small axillary clusters, actinomorphic, hypogynous, bisexual. Perianth shortly (4–)5(–9)-lobed. Stamens the same number as the perianth lobes and opposite them, erect in bud. Styles 2; stigmas linear. Ovary 1-celled, with 1 ovule. Fruit a flattened samara, winged all around, or a small drupe. Contains about 15 genera and some 200 species.

Annual or perennial herbs, usually with watery sap or white or yellow latex. Leaves spirally arranged, shallowly pinnately lobed to 2-pinnate; petioles present or absent; without stipules. Inflorescence umbellate or paniculate or with flowers solitary, terminal or axillary; flowers bisexual, hypogynous or rarely perigynous, actinomorphic. Sepals 2(–3), free or fused, normally falling early. Petals 4(–6) or absent, often large and brightly coloured, crumpled at first, normally falling early. Stamens numerous. Style 1, short or absent; stigma large and more or less peltate or capitate, lobed or rayed or more or less divided. Ovary of 2 to many fused carpels, 1(–2)-celled, with (2–)many ovules. Fruit a capsule, dehiscent or not.

Contains about 26 genera and 200 species, cosmopolitan but mainly in temperate and subtropical regions of the southern hemisphere.

Fedde, F. (1909). Papaveraceae – Papaveroideae. In Engler, A. (Edit.), Das Pflanzenreich IV. 102. Leipzig.

Grey-Wilson, C. (1993). Poppies. London.

Twining, usually fleshy, glabrous perennial herbs with potato-like tubers on their rhizomes. Leaves alternate; lamina ovate, entire, more or less cordate. Inflorescence a spike, raceme or racemose panicle; flowers bisexual. Sepals 2. Petals 5. Stamens 5, opposite petals. Styles 3. Ovary unilocular. Fruit an indehiscent, fleshy drupe, surrounded by persistent sepals and petals.

Contains 4 genera and 15 to 20 species in the tropics or subtropics.

Anredera Juss. Twining climbers with tuberous roots. Leaves alternate; lamina more or less fleshy, ovate, cordate, without stipules. Inflorescence a spike or raceme; flowers bisexual or unisexual. Perianth segments 5, united at base. Stamens 5, curved outwards in bud. Style 1, simple or 3-branched. Fruit a drupe, enclosed in the perianth, subglobose.

Contains between 5 and 10 species in tropical America.

Hooker, W. J. (1837). Boussingaultia baselloides. Bot. Mag. tab. 3620.

A. cordifolia (Ten.) Steenis Madeira Vine

Boussingaultia cordifolia Ten.; Boussingaultia baselloides auct.; Boussingaultia gracilis Miers; Boussingaultia gracilis var. pseudobaselloides (Hauman) Bailey; Boussingaultia gracilis forma pseudobaselloides Hauman

Perennial climber with oblong fleshy knotted tubers, sometimes of large size. Stems up to 6 m, rounded, woody at base, green, twining left to right, branched, glabrous. Leaves alternate, fleshy; lamina 2.5–10.0 cm, dark green on upper surface, paler beneath, ovate, acute or acuminate at apex, entire, cordate at base; petiole up to 25 mm, compressed, becoming broader above. Inflorescence an axillary raceme up to 30 cm, pendulous; pedicels with small subulate bracteoles at base and two ovate ones above; flowers bisexual or unisexual, fragrant. Perianth segments 5, united at base, white. Stamens 5; filaments curved outwards in bud; anthers yellow. Style 1, 3-lobed. Drupe not known to be produced in this country. Flowers 9–10.

Introduced. A persistent or established garden escape on a roadside at St Peter Port, Guernsey, in the Channel Islands. Native of subtropical South America; naturalised and sometimes invasive in subtropical and warm temperate regions elsewhere.