Subject: BEN # 216

From: Adolf Ceska <[email-masked]>
Date: Wed, 10 Mar 1999 22:43:30 -0800 (PST)

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No. 216                              March 10, 1999

[email-masked]        Victoria, B.C.
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 Dr. A. Ceska, P.O.Box 8546, Victoria, B.C. Canada V8W 3S2
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LAST CALL FOR BOTANY BC & BOTWA 1999 REGISTRATIONS [BEN # 214]

The  Cedar  Beach  Resort  is almost full with new registrations
still arriving. If you are interested in attending this  gather-
ing of British Columbia and Washington State botanists, and have
not registered yet, please give a call to Elizabeth Easton (250-
953-3488)   or   send   an  e-mail  message  to  Andy  MacKinnon
([email-masked]). We may have to look for  addi-
tional accommodation possibilities. - AC

EXPLOSIVE SECONDARY POLLEN PRESENTATION IN FAMILY MARANTACEAE
From: Helen Kennedy c/o <[email-masked]>

[In  BEN # 194 Dr. Ted Mosquin described "explosive pollination"
in flowers of bunchberry, Cornus canadensis. Shortly after BEN #
194 was posted, I got  a  note  from  Dr.  Helen  Kennedy  about
similar  explosive pollen distribution in some members of Maran-
taceae. Helen described it in the following paragraphs.  I  also
learned  that,  unlike  Amaranthaceae,  Marantaceae  are spelled
without "h" - Maranta  (arrowroot)  was  named  for  Bartolommeo
Maranti, Venetian botanist who lived around 1559. - AC]

Marantaceae  are  found in the lowland tropical forests of Asia,
Africa and the Americas. There  are  31  genera  and  about  520
species.  The  majority of the species, 80%, are in the American
tropics while 9% are African and 11% Asian. They are  understory
herbs  found  in  semi-deciduous  to  rainforest or cloud forest
habitats, ranging from sea-level to 1500 m, rarely  to  2000  m.
Marantaceae  are  readily  distinguished  from  all  other plant
families by 2 distinctive vegetative characters: 1) the  sigmoid
(S-shaped)  lateral  veins and the numerous parallel cross veins
of the leaf blade and 2) the presence of a region of specialized
cells just below the blade, termed the pulvinus, which  controls
the  movement  of  the leaves. The floral structure is also dis-
tinctive and is unique for  the  family.  Given  just  a  single
flower,  from any species in the world, one can immediately tell
it is Marantaceae. The style and cucullate staminode immediately
distinguish Marantaceae from all other families.

The style is a curved elastic spring  and  the  stigma  is  cup-
shaped.  The  style  is  held  under  tension  by  the cucullate
staminode which has a trigger. The flowers are borne in a  brac-
teate  inflorescence and are usually paired, each bract subtend-
ing a single to cymose series of paired flowers, the two flowers
of the pair being mirror images of each  other.  The  flower  is
irregular,  with  an  inferior ovary, the 3 petals fused basally
into a corolla tube, a single fertile stamen  with  a  1-locular
anther,  (2)3-4 staminodes with an elastic spring style and cup-
shaped stigma. There are 2 inner,  specialized  staminodes,  the
fleshy,  callose  staminode  and the hooded, cucullate staminode
which encloses the terminal portion of the style and stigma  and
(0)1-2  petaloid  outer  staminodes.  Like the Zingiberaceae and
Cannaceae, there is a single fertile stamen and the  showy  por-
tion  of  the  flower  consists  of  the highly modified sterile
staminodes.

The pollination mechanism  of  the  Marantaceae  is  termed  ex-
plosive,  secondary pollen presentation (Faegri and Van der Pijl
1966). Secondary pollen presentation is another floral character
which is shared with the sister group, Cannaceae,  but  in  Can-
naceae  it  is  not explosive. The style in Marantaceae is under
tension, and springs forward suddenly when released  during  the
pollinator's visit.

The  pollen  is  shed during the evening prior to anthesis while
the flower is still in bud, usually between 5:00 and 9:00 pm for
species whose  flowers  open  in  the  morning.  The  pollen  is
deposited  in a shallow depression on the back of the style just
behind the stigma. It is the upward growth of  the  style  which
forces  the  pollen  grains from the anther, and onto the stylar
depression ("stamp" of Andersson 1981). During the early morning
hours the stigma becomes receptive. At  anthesis  the  style  is
under  tension held in place by the cucullate (hooded) staminode
which is also under tension pulling in the  opposite  direction,
thus  maintaining  the  style  in a static equilibrium. When the
pollinator inserts its head into the flower  in  search  of  the
nectar,  it depresses the appendage, or "trigger", on the cucul-
late staminode thus releasing the style  which  springs  forward
bringing  the  stigma  in  contact  with the pollen (from a pre-
viously visited flower) on the pollinator's body and in the same
motion depositing its own  pollen  in  the  same  spot.  Lindley
(1819,  1826) was one of the first to describe the nature of the
floral parts, the pollen transfer and movement of the style. The
function of the spring style and  the  importance  of  the  pol-
linator  displacing the trigger in the pollination mechanism was
hypothesized by  Hildebrand  (1870a).  Delpino  (1869)  actually
observed  bees ("ape comune") visiting Thalia dealbata Fraser in
Florence, Italy.  The  mechanism,  especially  in  Calathea  and
related genera is quite precise with the pollen placement in the
narrow  proboscidial  fossa  beneath the bee's head. This is one
area where the bee is unable to groom or remove the pollen. When
the bee's proboscis is retracted after visitation  the  base  of
the proboscis covers the pollen, thus protecting it and prevent-
ing desiccation.

Each  flower has but a single chance to be pollinated, and, once
tripped the stylar  movement  is  irreversible.  The  difference
between  an  unvisited,  that is, untripped flower and a tripped
one is readily noticeable. Thus,  a  population  can  be  easily
surveyed  for  the  number  of  pollinated  versus  unpollinated
flowers (whether tripped or non-tripped) with just the use of  a
hand-lens.  Because  of  the  specialized floral morphology, the
pollen and the stigma are spatially separated prior to  tripping
(or  pollination)  and,  as  the stylar movement is irreversible
after tripping, its  position  prevents  any  pollen  from  sub-
sequently  entering  the  stigma  (in nature). This aspect is of
great advantage for crossing or selfing individuals in the field
or greenhouse as there is thus neither the  need  to  emasculate
the  flowers  prior  to  pollination nor to bag them afterwards.
There are a few exceptions  to  this  which  will  be  discussed
later.

Marantaceae  floral  structure  initially evolved in response to
bee pollination and the vast majority are still bee  pollinated.
Differences  in the number, shape and sizes of the floral parts,
such as length of corolla tube and shape  of  stigma  which  are
used  to distinguish the various genera are often adaptations to
different pollinators. The shift  to  the  more  precise  pollen
placement,  the  protection  of  the  pollen  by  the  cucullate
staminode and the distinctive morphological change in the flower
following pollination are  innovations  which  may  explain  the
greater  species richness or "success" of the Marantaceae versus
its sister group, the Cannaceae. A flower  differing  in  aspect
following  pollination,  whether  in  morphology or color, would
contribute to greater foraging efficiency by the bee pollinators
and presumably higher seed set for the plant. In several species
of Calathea, there is a distinct color change in addition to the
morphological change following pollination.  The  back  (abaxial
side)  of  the  style changes from an initial white or yellow to
dark brown or nearly black giving  a  clear  indication  to  the
pollinator  that  the  flower has already been visited. This was
first reported by  Hildebrand  (1870b)  for  C.  zebrina  (Sims)
Lindl.  and  is  characteristic  of  species  in  the  "Calathea
capitata group" (Kennedy 1988).

The Neotropical species are adapted primarily to pollination  by
the  long-tongued  Euglossine  bees  (Ducke 1901, Dressler 1968,
Kennedy 1974,  1978a),  while  Old  World  species  are  adapted
primarily  to  pollination  by  the  shorter-tongued  bees. This
adaptation is reflected in the difference of  the  average  tube
length  for  the Neotropical species versus those from the Asian
and African continents. The average tube  length  is  17.  6  mm
(N=81)  for the Neotropical species while only 4.6 mm (N=81) for
the Asian and African species.

In spite of the elaborate pollination mechanism in  Marantaceae,
there  has been a shift to varying degrees of autogamy (selfing)
in at least 44 species (ca. 8% of the  family).  With  increased
field  studies  and  the  introduction of species into Botanical
Gardens outside their natural ranges, more occurrences will come
to light. Early reports of spontaneous  seed  set  occurring  in
plants  growing  in  temperate  greenhouses or botanical gardens
gave a clear indication of  the  presence  of  autogamy  in  the
family.

The  actual  mechanism of autogamy was the same for all cases so
far examined, and occurs  during  the  pollen  transfer  process
within  the  bud. Thus, the pollen grains are already present in
the stigma well before anthesis. In most species,  the  orienta-
tion  of  the  stylar  tip is such that pollen is prevented from
entering the stigma (Fig. 3). A slight change in the orientation
of the tip of the style and stigma during  this  transfer  phase
can  result  in a few grains entering the stigmatic cavity while
the majority of the pollen grains are deposited, as normally the
case, just behind the stigma in the stylar  depression  (Kennedy
1978b).  When  the  stigma  later  becomes  receptive, early the
following morning, the pollen in the stigma  can  germinate  and
thus result in fertilization and seed set.

References:

Delpino,  F.  1869.  Breve  cenno  sulle  relazioni biologiche e
   genealogiche delle Marantaceae. Nuovo Giorn.  Bot.  Ital.  1,
   93-306.
Dressler, R. L. 1968. Pollination by Euglossine beees. Evolution
   22, 202-210.
Ducke, A.  1901.  Beobachtungen �ber Bl�tenbesuch, Erscheinungs-
   zeit etc. der bei  Par   vorkommenden Bienen. Zeitschr. Syst. 
   Hym. Dipt. 1, 25-32; 49-51; 60-63.
Faegri,  K. & L. van der Pijl. 1966. 'The Principals of Pollina-
   tion Ecology' (Pergamon Press: London)
Gris, A. 1859. Observations sur la  fleur  des  Marant‚es.  Ann.
   Sci. Nat. IV. 12, 193-219.
Hildebrand,  F.  1870a.  Botanische Notizen aus einem Briefe von
   Fritz M�ller. (Itajahy, den 7. dezember 1869.)  Bot.  Zeitung
   28, 273-275.
Hildebrand,  F.  1870b.  F. Delpino's weitere Beobachtungen �ber
   die Dichogamie im  Planzenreich mit Zus„tzen und Illustratio-
   nen. Bot. Zeitung 28, 617-625.
Kennedy,  H.  1974.  Pollination and systematics of the "closed-
   flowered" species of Calathea  (Marantaceae).  Ph.D.  Thesis,
   University of California, Davis. 301 p.
Kennedy,  H.  1978a. Systematics and pollination of the "closed-
   flowered"  species  of  Calathea  (Marantaceae).   Univ.   of
   California Publ. Bot. 71: 1-90, 20 plates.
Kennedy,  H.  1978b.  Marantaceae.  Taxonomy  -- Classification.
   Marantaceae Newsletter 1, 3-9. (An informal xeroxed  newslet-
   ter circulated by the Lyon Arboretum, Hawaii, USA)
Kennedy,  H.  et  al.  1988.  Marantaceae. In Harling, G. and L.
   Andersson [eds.] Flora of Ecuador. 32, 13-191.
Lindley, J. 1819. Maranta zebrina. Bot. Reg. 5, t. 385.
Lindley, J. 1826. Calathea violacea Bot. Reg. 12,  t.  962  text
   sub t. 961.

RARE NATIVE VASCULAR PLANTS OF BRITISH COLUMBIA - ANNOUNCEMENT

Douglas, G.W., G.B. Straley, and D. Meidinger. 1998. Rare native
   vascular  plants  of British Columbia. B.C. Conservation Data
   Centre, Ministry of Environment, Lands & Parks, Victoria, BC.
   v + 423 p. ISBN 0-7726-33307-X Cost: CND$39.95

   Ordering information:
   Crown Publications Inc.,  521  Fort  Street,  Victoria,  B.C.
   Canada V8W 1E7, Phone: (250) 386-4636, Fax: (250) 386-0221

This  manual includes a summary of the status of rare and endan-
gered native vascular plant taxa  in  the  province  of  British
Columbia. Over 600 plants are dealt with in this volume with the
main  body of the book arranged alphabetically by genus/species.
It contains the synonyms,  common  name,  habitat  requirements,
world  distribution,  provincial  distribution map, line drawing
and conservation ranking for each rare plant taxon.

ILLUSTRATED FLORA OF BRITISH COLUMBIA - ANNOUNCEMENT

Douglas, G.W., G.B. Straley, D. Meidinger and  J.  Pojar.  1998.
   Illustrated  flora  of  British Columbia. Vol. 1. Gymnosperms
   and Dicotyledons (Aceraceae through Asteraceae). Ministry  of
   Environment,  Lands  and Parks, and Ministry of Forests, Vic-
   toria, BC. 436 p. ISBN 0-7726-3685-0 (set) [soft cover] Cost:
   CND$30.00

Douglas, G.W., G.B. Straley, D. Meidinger and  J.  Pojar.  1998.
   Illustrated  flora  of British Columbia. Vol. 2. Dicotyledons
   (Balsaminaceae through Cucurbitaceae). Ministry  of  Environ-
   ment, Lands and Parks, and Ministry of Forests, Victoria, BC.
   v  +  401  p.  ISBN  0-7726-3685-0  (set)  [soft cover] Cost:
   CND$30.00

   Ordering information:
   Crown Publications Inc.,  521  Fort  Street,  Victoria,  B.C.
   Canada V8W 1E7, Phone: (250) 386-4636, Fax: (250) 386-0221

The first two volumes, of an eight volume series on the vascular
plant  flora of BC, have now been printed. These volumes include
the  Gymnosperms  and  Dicotyledons  (Aceraceae  to  Asteraceae)
[Volume  1]  and the Dicotyledons (Balsaminaceae to Cuscutaceae)
[Volume 2]. The treatment includes keys to genera  and  species,
habitat/range  annotations, technical descriptions and illustra-
tions for each taxon.

VEGETATION IN EASTERN NORTH AMERICA - BOOK REVIEW
From: Spribille_Toby/[email-masked]

Miyawaki, A., K. Iwatsuki & M.M. Grandtner (eds.) 1994.  Vegeta-
   tion in eastern North America: vegetation system and dynamics
   under  human  activity in the eastern North American cultural
   region in comparison with Japan. ix + 515  p.  University  of
   Tokyo Press. ISBN 0-86008-494-9 [hard cover] Price: US$250.00

This  book  is a compendium of papers resulting from the Eastern
North American Vegetation Survey (ENAVS), a  three-year  program
to  survey  the  flora  and  vegetation  from Quebec to Florida,
funded by the Japanese Ministry of Education, Science  and  Cul-
ture.  The  field  work, by a team of Japanese vegetation scien-
tists with assistance from  Canadian  and  American  colleagues,
included  sampling  of  about 1,300 releves, involving travel of
over 20,000 km in the space of a total of fourteen weeks.

The text is divided into  five  sections  (natural  environment,
comparison  of  floras, vegetation system and dynamics, ecology,
and conservation and rehabilitation) which  in  turn  contain  a
total of seventeen papers by participants from Japan, the United
States  and Canada. It is as much a work on phytogeography as it
is on vegetation science. An underlying  theme  in  all  of  the
papers  is  a comparison of Japan and eastern North America from
the floristic, syntaxonomic and ecological perspectives.

The book is not only a compendium of existing information on the
respective vegetation and floras, but also provides  some  valu-
able  first-time  descriptions for eastern North America. A full
48 phytosociological tables  (both  releve  and  constancy)  are
included   for   alpine   meadows,  boreal  coniferous  forests,
deciduous  and  evergreen  broad-leaved  forests  and   mangrove
vegetation. The floristic and ecological summarization is accom-
panied  by  many  black-and-white  photographs  and a section of
beautiful colour plates. All in all,  the  book  is  a  valuable
addition  to  the knowledge of eastern North American vegetation
and will doubtless be an indispensable reference on the topic of
eastern North American-east Asian phytogeography  far  into  the
future. One could only wish the book was more affordable.

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