Figure 1: simple uniseriate, unicellular hair
Figure 2: simple uniseriate, multicellular hair
INTRODUCTION
Identification of plants is mostly done using certain macro-morphological characteristics
such as e. g. number of sepals and petals. The morphological characteristics
that are commonly used to identify and rank plants within the plant family Solanaceae
are described in general terms on the page "General Characteristics"
in this website. Less common characteristics however, have been used to characterize
Solanum species. Examples of this are Bitter G. (ref.
85 and 101)
based on sclerotic bodies, Martius et al. (ref. 394)
based on the fruits, Symon D.E. (ref. 967)
based on the fruits and anthers, Whalen M.D. (ref. 1036)
based on the inflorescence, Gunn C.R. (ref. 474)
based on de seeds and Seithe A. (ref. 893,
894 and 895)
based on the prickles and hairs. This page gives information on the types of
hairs that can be found in Solanum species and which can be of help to
identify certain species. The use of micro-morphological characteristics such
as hair type however, as a general key for ranking is questionable.
1. Simple hairs (simplex)
1.1 Uniseriate (uniseriatis, figs. 1 ,2). Consists of one row of cells (unbranched).We distinguish unicellular (unicellularis, fig 1; e.g. the hairs on the upper surface of the leaves of Solanum chiapense Roe (voucher: Roe, Roe & Mori 986, Chiapas, Mexico ), bicellularis, oligocellularis, pluricellularis and multicellularis (e.g. the hairs on the calyx of Solanum triflorum Nutt. (voucher: S.T. Dillon 53, Manitoba,Canada, fig. 2).
|
Figure 1: simple uniseriate, unicellular hair
|
Figure 2: simple uniseriate, multicellular hair
|
Click on thumbnail to see larger picture
1.2 Multiseriate (multiseriatis)
Several to many closely lying against each other (accumbentibus). The stalks
of the many complex hairs are often multiseriate. The spiny hairs of Solanum
marginatum L. (figure 3) can also be considered as multiseriate
(voucher: D.Ugent 2261, Michoacan, Mexico) unbranched, multiseriate bases and
one single cell on the top.
|
Figure 3: simple, unbranched, multiseriate hair
|
Click on thumbnail to see larger picture
2. Stellate (stellatus)
2.1 Porrect-stellate (porrectus-stellatus).
Resembling the spines of some cacti: consisting of one central up-raising stalk
and 2-16 horizontal radiar stalks ranked around the ventral stalk. The central
stalk can be very tiny, or even absent, but also as large as the horizontal
ones.
Example 1: sessile, up-raising-stellate, one central stalk and 2-16 horizontal
stalks on the upper surface of the leaves of Solanum blodgettii Chap.
(fig.4, voucher. Ugent 6000, Monroe Co. Florida).
Example 2: sessile, porrect-stellate, long central ray on the upper surface of Solanum umbellatum Mill. (fig. 5, voucher Mick & Roe 315, Oaxaca, Mexico).
Example 3: multiseriate, stalked, porrect -stellate, short central ray. Hairs on stem of Solanum hispidum Pers. (fig.6, voucher Ugent & Flores 2460, Veracruz, Mexico).
Example 4: Short stalked, porrect-stellate, short central ray. Upper
surface of the leaves of Solanum elaeagnifolium Cav. (fig.
7, voucher C.C. Collins 1, Payne Co. Oklahoma). In fact this is a stage
of transition to pelate (see peltate).
Example 5: short stalked, porrect-stellate, short central ray, lateral ray somewhat fused. Stem of Solanum mandonis Heurck & Muell.Arg. (fig.8, voucher C. Vargas C. 4576, Cuzco, Peru). Peltate (peltatus). Scale- or shield hair. In fact the same as porrect-stellate hairs, but the horizontal stalks are sticked together over a great part of the length. There can be a central stalk or a group of cells in the form of a bud (umbo). The examples under 4 and 5 are transition forms to peltate.
Example 6: peltate, short stalked, umbo rather than a central ray. Hairs on the surface of the leaves beneath of Solanum swartzianum R&P (fig. 9, voucher: Mexia 4363 Minas Gerias, Brazil).
| Figure 4: sessile, porrect-stellate, short central ray | Figure 5:multiseriate, stalked, porrect -stellate, long central ray | Figure 6: multiseriate, stalked, porrect -stellate, short central ray. |
| Figure 7:Short stalked, porrect-stellate, short central ray | Figure 8:short stalked, porrect-stellate, short central ray, lateral ray somewhat fused | Figure 9: peltate, short stalked, umbo rather than a central ray |
Click on thumbnail to see larger picture
2.2 Multiangulate (multiangulatis)
Brush- or bristle hairs, 2-16 hairs straight up form the centre. In this case
it is advised to count the number of hairs for reasons of determination. Sometimes
there are intermediate forms to echinoid hairs (e.g. fig. 12,
Solanum mauritianum Scop.). This species belongs here because it is still
possible to count the number of stalks and because the bases of the stalks are
not as compact as it is in echinoid hairs.
Example 1: Two-rayed, stellate, arising from raised base (fig.
10, Roe, Roe & Mori 986, Chiapas, Mexico).
Example 2: Multiseriate-stalked, multiangulate. (fig.11, peduncle of Solanum bicolor Willd.; voucher: Britton & Mendelson 1584, Trinidad).
| Figure 10: Multiangulate, two-rayed, stellate, araising form raised base | Figure 11: Multiseriate-stalked, multiangulate. | Figure 12:Multiangulate intermediate form to echinoid. |
Click on thumbnail to see larger picture
2.3 Multiradiate (multiradiatus)
Brush- or bristle hair, several stalks. Within this group we find the multiangulated
types of hairs as described above, but with the restriction that we are dealing
with hairs with several stalks. Confusion with the echinoid types is possible.
2.4 Echinoid (echinate/echinatus).
Brush- or bristle hair composed of a great number of stalks (more than 20) which
are projected from the central stalk under different angles. The central axis
looks like a solid ball due to the compact bases of the stalks (fig. 13 and
14). The differences between multiangulate and echinoid is arbitrary and artificially,
but in practice is works because most of the species can be grouped easily in
one of the two groups. If the number of stalks is uncountable than the hair
is classified in the echinoid group.
Example 1: Sessile, echinoid. Stem of Solanum erianthum D.Don (fig. 13, voucher: Roe & Roe 2206, Sant Louis Potosi, Mexico).
Example 2: Stalked, echinoid. Peduncle of Solanum brevipedicellatum Roe. (fig.14, Voucher: Roe & Mori 741, Quezaltenango, Guatemala).
|
Figure 13:Sessile, echinoid
|
Figure 14:Stalked, echinoid.
|
Click on thumbnail to see larger picture
3. Dendroid (dendritic/dendriticus).
In the shape of a tree, with stalks like branches situated on a central stem.
3.1 Forked (furcate).
Pitch forked hairs. Real forked hairs are not common in the Solanaceae .On the
other hand the homogeneous two-stalked hair is (fig. 10 two-stalked hair, stellate,
coming from a central up-raising base. Voucher: Roe & Mori 986, Chiapas,
Mexico).In fact they are considered to be more a combination of two simple hairs
than it is a real forked hair.
Example 1: Calyx of Solanum sysimbrifolium Lam. (fig.
15, voucher: Bang 614, Cochabamba, Bolivia).
|
Figure 15: Forked hair
|
Click on thumbnail to see larger picture
3.2 Dendritic (dendriticus)
Knot-hair, tree-hair. Mostly consisting of a flexible main stem with a few to
many diverged side-branches, ad-randomly divided along the stem Fig
16
Example 1: surface of the leaves underneath of Solanum capsicastrum Link.(fig. 16, voucher: Morong 1529, Pilcomayo River, Paraquay).
Example 2: surface of the leaves underneath of Solanum ochrophyllum Heurck & Muell.Arg.Arachnoid or modified dendritic.fig.17, voucher: Bang 1931, Bolivia).
|
Figure 16: dendritic hair
|
Figure 17: dendritic hair
|
Click on thumbnail to see larger picture
4. Some commonly seen, modified types of hair
4.1 Glandulair (glandulosus)
Glands. These hairs contain budlike swollen secretory-organs at the top of the
hairs.
Example 1: Glandulair, multiangulate (glandulosus, multiangulatus). Stem of Solanum abutiloides (Griseb.) Bitter & Lillo. (fig. 19, voucher: cultivated species in Argentina.
Example 2: Simple, glandulair (simplex, glandulosus). Simple gland- hair. Stem of Solanum heterodoxum Dunal.(fig 18, voucher: R.C.Jackson 6730, Coahuila, Mexico).
|
Figure 18: Simple,glandular hair
|
Figure 19:Glandular, multiangulate hair
|
Click on thumbnail to see larger picture
4.2 Geminate-stellate (Geminus, stellatus).
A modification of the porrect-stellate type consisting of a central up- raising
axis and two crowns of stalks above each other instead of one.
4.3 Dendritic-echinoid (dendriticus-echinatus).
Shaggy, in the form of a chandelier (abietiforme), a modification of the echinoid
type of hair with a prolonged axis. This means a central hair consisting of
several rows and from there several crowns of stalks with open spaces in between
the crowns.
|
Figure 20: Dendritic-echinoid hair
|
Figure 21: Modified dendritic-echinoid. Furfuraceous.
|
Click on thumbnail
to see larger picture
Example of differences in hair types as a supporting
tool for identification of related Solanum species.
INTRODUCTION
There are six species in the Solanaceae considered noxious in California: Solanum
carolinense L., Solanum dimidiatum Raf., Solanum elaeagnifolium
Cav., Solanum lanceolatum Cav., Solanum marginatum L.f.
and Solanum rostratum Dunal. Their impact on agriculture is big
either by reducing crop yields, because the foliage and berries are toxic to
livestock or because they are alternate hosts for disease and insect pests in
a broad range of crops in California. In a first glance the resemblance of five
of them is quiet similar being prickly herbs with more or less the same flower
in size and colour (Solanum rostratum Dunal is easily recgonized by the
bright yellow flower and the typical form of one of the anthers).. However,
several macro-characteristics such as habit, length and shape of mature leaves,
diameter and colour of the berries, length and colour of the prickles and inflorescence
can be used to differentiate between the species. The differences between the
stellate hairs can be used as a supporting tool for identification of these
related Solanum species.
SPECIES INVOLVED
| Solanum species | Characteristics of the stellate hairs | |
| Solanum carolinense L |
Minute stellate hairs, yellowish, sessile & short-stalked, rays mostly 5-7, central ray same length or some what longer than the radiate rays |
 |
| Solanum dimidiatum Raf. | Minute stellate hairs, yellowish, sessile & short-stalked,
rays mostly 6-8, central ray same length or somewhat smaller than the radiate
rays. |
 |
| Solanum elaeagnifolium Cav. | Minute stellate hairs, silver-white, +/- sessile, rays mostly 9-14, shield like at centre, central ray usually much smaller than the radiate rays (see figure 7). |  |
| Solanum lanceolatum Cav. | Minute stellate hairs, more or less straw-colored, sessile & stalked, rays mostly 5-9, central ray same length of somewhat smaller than the radiate rays |  |
| Solanum marginatum L.f. | Minute stellate hairs, white, more or less iridescent, stalked, rays mostly 7-9, central ray usually more or less the same length as the radiate rays (see figure 3). |  |
| Solanum rostratum Dunal | Yellowish, sessile & stalked, rays mostly 6-8, central ray often the same length or somewhat longer than the radiate rays |  |
Pictures with courtesy of:
Solanum carolinense L. : staff CDFA, California Dept. of Food & Agriculture, Integrated Pest Control Branch.
Solanum dimidiatum Raf.: Douglas Barbe, California Dept. of Food & Agriculture, Botany Laboratory.
Solanum elaeagnifolium Cav.: Douglas Barbe, California Dept. of Food & Agriculture, Botany Laboratory.
Solanum lanceolatum Cav.: T. Fuller, California Dept. of Food & Agriculture, Botany Laboratory.
Solanum marginatum L.f. staff CDFA, California Dept. of Food & Agriculture, Botany Laboratory.
Solanum rostratum Dunal: Larry Blakely
.
