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Tilia
cordata Mill., T.
platyphyllos Scop., T. ×europaea L.
Standardized Common
Name: Linden
Other Common Names: Basswood, Lime Tree
Family: Tiliaceae
Taxonomy: Tilia
includes about 45 species of trees. Those used as Linden are among five, plus
one common hybrid, that are native to Europe. The nomenclature of these species
has been muddled. Synonymy of T. cordata includes a portion of T.
europaea L. as it was previously (and too broadly) defined. Tilia
platyphyllos is divided into three subspecies, and includes the former T.
cordifolia Besser. The name T. officinarum Crantz, recently proposed
for rejection by C. D. Pigott, referred to both of these species (among others).
T. europaea, which (as properly circumscribed)
represents a hybrid of T. cordata and T. platyphyllos, is
frequently called T. × vulgaris Hayne; another synonym is T.
intermedia DC.
Description: Trees up to 30–40 m
tall, with lower trunks branchless and crowns dome-shaped. Bark grayish,
fissured or cracked. Leaves alternate, petiolate, stipulate with deciduous
stipules, broadly ovate to suborbicular, (3–)6–9(–12) cm long; base cordate,
often oblique; apex acuminate; margins more or less serrate. Inflorescence a
few-flowered cyme, subtended by a bract; bract 6–9 cm long, narrowly oblong,
membranous, somewhat leaflike; lower portion of peduncle fused to bract.
Flowers regular, sepals 5, free except at base, broadly lanceolate with acute
apices; petals 5, free, oblong to lanceolate, 6–7 mm long, whitish to
yellowish; stamens numerous; ovary 5-loculed, stigma 5-lobed. Fruit a nut,
1-loculed, 6–8(–10) mm long, globose, ovoid or pear-shaped, 5-ribbed or smooth,
grayish; seeds 1–3.
Parts
in Commerce:
Flowers. Fragments of leaflike bracts and developing fruits are usually
present.
Identification: The flowers of all
official species are virtually identical.
- Fragments of
strap-shaped bracts membranous, pale green, glabrous, with netted veins;
basal portions have thickened midrib where stalk of inflorescence is fused
to bract
- Sepals 5, with
short hairs especially inside and near apex of outside
- Petals creamy to
yellowish
- Petals 5, no
petalloid staminodes present
- Petals 6–7 mm
long, oblong to lanceolate
- Stamens numerous
- Ovary densely
pubescent with short hair; style hairless
- Odor weak,
aromatic
- Taste slightly
sweet and mucilaginous
Fruit features vary among official species, as follows:
|
T. cordata
|
T. ×europaea
|
T. platyphyllos
|
Fruit
size, shape
|
6(–8)
mm, more or less round
|
(6–)8
mm, usually broadly ovate, often with prominent style base at apex
|
7–10
mm, pear-shaped or nearly round, with pointed apex
|
Pericarp
|
Membranous,
sometimes with 5 faint ribs
|
Woody,
with 5 faint ribs
|
Woody,
with 5 strong ribs especially at apex
|
Epidermis
of fruit
|
Immature
ovaries fuzzy, mature fruit mostly hairless
|
Typically
fuzzy at maturity
|
Covered
with thick layer of fuzz
|
Adulterants: Other species of Tilia
are sometimes substituted for the three official species; these may include T.
americana L., T. chinensis Maxim., T. ×euchlora C. Koch, T. mandschurica Rupr., and T.
tomentosa Moench, depending upon origin of the material. The flowers and
fruit of most species appear very similar to those of the official species. The
following features indicate mistaken identity:
- Unpleasant odor or taste
- Bract fragments densely hairy or with pink midrib
- Flowers with petalloid staminodes
- Stamens not numerous
- Lower portion of style hairy
- Fruit surface warty
- Fruit >10 mm in diameter
References:
Browicz K. Tilia. In: Tutin TG, Heywood VH, Burges NA, et al., eds. Flora
Europaea. Vol. 2. Cambridge: Cambridge University Press; 1968:247–248.
Pigott CD. Two proposals to maintain the names Tilia
cordata and T. platyphyllos (Tiliaceae) in their current use.
Taxon. 1997;46:351–353.
Pigott CD, Sell PD. Nomenclature of the European
species of Tilia: I. Tilia europaea L. Kew Bull.
1995;50:135–139.
Rushforth K. Collins Guide to the Trees of
Britain and Europe. London: HarperCollins; 1999.
Wichtl M, ed. Herbal Drugs and
Phytopharmaceuticals, 3rd English
ed. Stuttgart: medpharm Scientific Publishers and Boca Raton, FL: CRC Press;
2004:611–613.
Figure 76: a–b, Tilia
platyphyllos fruit and
inflorescence; c, T. cordata fruit;
d, T. ×europaea fruit.