Transcript Phylogeny of the Acanthaceae, Acanthus Family Lisa Markovchick-Nicholls Biology Department, San Diego State University Family Characterization Diversity & Biogeography 229 genera and >3000 species. Habit &

Phylogeny of the Acanthaceae, Acanthus Family
Lisa Markovchick-Nicholls
Biology Department, San Diego State University
Family Characterization
Diversity & Biogeography
229 genera and >3000 species.
Habit & Characteristics
(Hickman 1993, Simpson 2006)
Usually annual or perennial herbs or shrubs.
Mostly pan-tropical, from the tropics to
temperate regions (Simpson 2006, Stevens
2001). See Figure 1.
Leaves generally simple and opposite.
Inflorescence a bracted cyme, spike, or raceme
of solitary flowers.
Flowers bisexual, nearly radial to 2-lipped, calyx
deeply 4-5 lobed, and corolla 4-5 lobed (Fig. 2).
Stamens 2 or 4 and epipetalous. Anther sacs
sometimes dissimilar in size or placement. See
Figure 3 for example.
Ovary superior with axile placentation (Fig. 2).
Fruit explosively dehiscent loculicidal capsule.
Nectaries often form disk at ovary base (Fig.5).
Exemplar Description:
Economic Importance
Several cultivated ornamentals (Simpson
2006).
Figure 1. Biogeography from Heywood
1985: Note pan-tropical distribution.
Specific family members also reportedly
have a wide range of medicinal uses, including:
Figure 2. Justicia californica,
specimen LMARKOV16. Top:
Perianth. Note bilabiate, sympetalous
corolla. Bottom: Ovary Cross-section.
Note 2 locules with one ovule per
locule, and axile placentation.
As antioxidants (Chen et al. 206)
To relieve drug addiction symptoms
and increase neuron activity in brain
regions responsible for reward and
locomotor behavior (Thongsaard et al.
2005).
Justicia californica (Benth.) D. Gibson
L. Markovchick-Nicholls. LMARKOV16, SDSU. See Figures 1-5.
Floral formula: K (5) C (5) A 2 G (2), superior, hypogynous.
Plant a terrestrial, perennial, hermaphroditic,
shrub, 0.3 to 2 m tall tall. Aerial stem erect,
caulescent. Twigs puberulent. Thorns,
spines, prickles, and spur shoots absent.
Leaves simple, petiolate, stipulate, drought
deciduous, opposite, decussate, inclined,
slightly recurved and conduplicate. Petioles
terete, green, 5-10mm long, inclined. Stipules
adaxially and abaxially puberulent, 1 mm long.
Leaf blade light green to dark green, ovate to
triangular, 1.5-2.5 cm long, 1-1.5 cm wide,
rounded to cordate, entire to sparsely serrate,
acute to cuspidate, pinnate-netted, puberulent,
with veins slightly protruding. Inflorescence
terminal, bracteate, raceme, 8-13 cm long, 5-6
cm wide from corolla apex to corrolla apex,
inclined, bisexual / hermaphroditic, puberulent.
Inflorescence bracts basal, 8-9 mm long,
light green, petiolate, narrowly elliptic, cuneate,
entire, acute to acuminate, adaxially and
abaxially puberulent. Flowers perfect,
caducous, ~3.5 cm long, 5 mm wide, opposite,
inclined to ascending, zygomorphic,
pedicellate. Pedicel 8-9 mm long, terete.
Flower bracts caducous, basal, 8-9 mm long,
light green, petiolate, narrowly elliptic, cuneate,
entire, acute to acuminate, adaxially and
abaxially puberulent. Hypanthium absent.
Perianth dichlamydeous. Calyx valvate,
synsepalous (deeply lobed but fused at base),
radial, 5-9 mm long, green to purple-brown,
adaxially and abaxially puberulent.
Sepals 5, 4-5 mm long, narrowly triangular,
fused, entire, acute. Corolla bilabiate to
cucullate, valvate, sympetalous, dark red with
streaks of yellow in center, zygomorphic, 2-4 cm
long, puberulent, prominent veins, with 2
becoming stamens.
Petals 2 lips, but 5 lobes, fused, entire, rounded,
13-15 mm long, inclined, anterior lip cernuous to
squarrose. Stamens uniseriate, 2, filamentous,
epipetalous, whorled, inserted, epipetalous.
Staminodes absent. Filaments terete,
yellowish, 15-20 mm long. Anthers basifixed,
dithecal, longitudinal, red, 3-4 mm long, narrowly
elliptic, and dehisce downward, with thecae
offset. Pollen yellow. Gynoecium syncarpous.
Perianth/androecial position hypogynous.
Ovary superior, green, 3-3.5 mm long,
ellipticoid, but irregular and bumpy, puberulent at
base. Style 1, terminal, linear, dark pink to dark
red, inclined, straight with corrolla attached,
coiled when corolla falls off. Stigma 1, terminal,
globose, viscid. Single donut-shaped
nectariferous disk at bottom of ovary. Carpels
2. Locules 2. Placentation axile. Ovule 1 per
carpel. Fruit a 2-valved capsule, green,
ellipticoid, but irregular and bumpy, 10 mm long,
5 mm wide, puberulent.
Palynology
Pollen reticulate and tricolporate, but with
several (~14) distinctive circular regions in two
rows down the center of the axis of the aperture.
Aperture trident-shaped at ends. See Fig. 4.
Phylogenetic Relationships
The Acanthus family are part of the Lamiales. They are known to be differentiated from close sister
taxa (“Near Out-Groups in Figure 6) by their explosively dehiscent loculicidal capsules. Within the
family, there are four major lineages (depicted in Figure 6). The Acanthus lineage are distinct in
having 4 monothecous stamens (McDade & Moody 1999). The Justicia lineage are often marked by
a reduction of the androecium to 2 fertile stamens (see exemplar description) and also seem to lack
the hygroscopic hairs present on seeds of the Barleria and Ruellia lineages (McDade & Moody 1999).
The Barleria and Ruellia lineages also have corolla aestivation types unique within the family,
quincuncial and left contort ( in contrast to imbricate or convolute, McDade & Moody 1999).
Relationships among the family and sister taxa are still commonly debated. For instance, those listed
as “Near Out-Groups” in Figure 6 were thought to be part of the Acanthaceae until recently (McDade
et al. 2000). In some genera a curtain of filaments covers the nectary (see Figure 7 top),
hypothesized to prevent nectar evaporation, function in depositing pollen on visiting insects, increase
stability and precision of pollination mechanisms in large flowers, or restrict nectar access. The
specific form or type of filament curtain (Figure 7, bottom) appears to be useful in discriminating
among members of the Ruellia lineage (Manktelow 2000).
Literature Cited
Chen, Fu-An, An-Bang Wu, Pochuen Shieh, Daih-Huang Kuo, and Chi-Ying Hsieh. 2006. Evaluation of the antioxidant activity of Ruellia
tuberose. Food Chemistry 94 (1) : 14-18.
Figure 3. Stamen: note inserted nature,
puberulent filament, and offset thecae.
Figure 4. Pollen and aperture: Note reticulate
sculpturing and distinctive aperture.
Figure 5. Ovary, nectary, and
style: Note donut-shaped
nectariferous disk at base of
superior ovary, and coiled
style after corolla falls off.
Filament
curtain
common
Stamens
reduced to 2,
hygroscopic
seed hairs
absent
4
monothecal
anthers
Explosively
dehiscent
fruit
Figure 6. Acanthaceae Cladogram from
McDade et al. 2000. Note close relatives and 4
main lineages.
Figure 7. Filament curtain
from Maktelow 2000. Top:
Curtain of filaments
shields nectary. Bottom:
Four types of filament
curtains in Ruellia lineage.
McDade, L. A. and Michael Moody. 1999. Phylogenetic relationships among Acanthaceae: Evidence from Noncoding trnLtrnF chloroplast DNA sequences. American Journal of Botany 86 (1): 70-80.
McDade, L. A., S. E. Masta, Michael L. Moody, and Elizabeth Waters. 2000. Phylogenetic relationships among Acanthaceae:
Evidence from two genomes. Systematic Botany 25(1): 106-121.
Heywood, V.H. 1985. Flowering plants of the world. Prentice Hall, Englewood Cliffs, NJ.
Stevens, P.F. 2001 onwards. Angiosperm Phylogeny Website. Version 6, May 2005 [and updated continuously since].
http://www.mobot.org/MOBOT/research/APweb/.
Hickman, James C. (ed). 1993. The Jepson Manual: Higher Plants of California. University of California Press, Los Angeles.
Simpson, Michael G. (2006). Plant Systematics. Elsevier Academic Press, San Diego.
Manktelow, M. 2000. The filament curtain: a structure important to systematics and pollination biology in the Acanthaceae. Botanical
Journal of the Linnean Society 133: 129-160.
Thongsaard, Watchareewan, Charles A Marsden, Peter Morris, Malcolm Prior, Yasmene B. Shah. 2005. Effect of Thunbergia
laurifolia, a Thai natural product used to treat drug addiction, on cerebral activity detected by functional magnetic resonance
imaging in the rat. Psychopharmacology 180 (4) : 752-760.