Acharagma aguirreanum

Acharagma aguirreanum (Glass & R.A. Foster) Glass, Guía Identif. Cact. Amenazadas México 1: [1] [AC/AG], 1998. Gymnocactus aguirreanus Glass & R.A. Foster, Cact. Succ. J. (Los Angeles) 44: 80 (figs.). 1972. Thelocactus aguirreanus (Glass & R.A. Foster) Bravo, Cact. Suc. Mex. 25: 65, 1980. Escobaria aguirreana (Glass & Foster) N.P. Taylor, Kakteen Sukk. 34: 185, 1983. Type: C. Glass & R. Foster 2206 Cañon Verde eastern slopes of Sierra de la Paila, Coahuila, Mexico, 24 Apr 1970; holotype: POM (jpg 1.7 mb).


Plants usually solitary. Stems deeply seated, the above-ground portion depressed globose (but not flat topped), globose or short cylindroid, soft, medium green to purple, 3-5(-12) cm high, 5-7 cm in diameter. Tubercles arranged in rows (5/8 or 8/13 spirals), well developed, fleshy, somewhat flexible, 10-15 mm wide basally, protruding 5-6 mm, ± 4.5 mm in mid diameter. Central spines 2-5(-6), largest 12-29 mm long, others 20-30 mm long, purplish gray to orange-tan, often difficult to distinguish from upper radials. Radial spines 13-16, often in two series, (7-)8-15 mm long. Flowers yellowish to reddish-yellow, 15-18 mm long, to 20 mm in diameter. Fruits greenish-purple, to 9-12 mm long, 3.5 mm in diameter. Restricted to southeastern and central Coahuila, along the western edge of the Sierra de la Paila, and Sierra San Marcos. Steep mountainsides of igneous rock, in dense scrub; 1350-1550 m elevation.


Seed morphology and seed coat micromorphology: Seed broadly oval, of the Arequipa-type, small, 1.12-1.35 mm long (mean= 1.28 mm), 0.71-0.97 mm dorsal-ventral height (mean= 0.88 mm), 0.68-0.82 mm wide (mean= 0.72 mm), matt, black, boarder expanded around and constricted above the hilum; lacking multicellular sculpture; no distinction of the periphery, i.e., no dorsal crest; cells (jpg 42 kb) uniform, elongate, anitclinal boundaries inconspicuous, generally straight, relief par-concave; micro-relief verrucose; hylem small oblique, superficial, 0.29-0.53 mm long (mean= 0.35 mm), 0.21-0.35 mm wide (mean= 0.29 mm), hylem and micropyle separate or conjunct, the fibrous band separating them 0-0.09 mm (mean= 0.03 mm); hylem-micropylar region 0.41-0.56 mm long (mean= 0.48 mm).

Pollen Morphology: Pollen of Acharagma aguirreanum is spherical to slightly oblate, elongate in the polar axis, 43-47 microns polar diameter, 41-44 microns equatorial diameter, tricolporate (3 apertures, each aperture composed of a colpus, 32-45 microns long, and a pore), exine pertectate, the tectum bearing pores, 0.5-2.5 microns in diameter, and spinule processes, 0.25-0.45 microns high and in diameter.


Spine Micromorphology (jpg 398 kb): At sexual maturity, the radial and central spine differ little in color, but do vary in length and diameter. Cells are elongate in the direction of the long axis of the spine, rectangular, trapezoidal, or rhomboidal. Along the shaft the transverse walls are frequently separated from one another, toward the acute, distal tip, the transverse walls acute and not separated, cells 60-165 microns long, 11-20 microns wide. The cells are smooth, lacking papillae.

What’s new in the Porter Lab…

Two new species of Loeselia (Polemoniaceae) from central Mexico are being described and illustrated in Systematic Botany vol. 34.  Both are known only from small areas in the Balsas Depression of the state of Michoacán.  Loeselia tancitaroensis occurs in pine-oak forest on the foothills of Cerro Tancítaro.  It is similar to the Oaxacan endemic L. ruprestis, from which it differs in possessing linear to linear-lanceolate inflorescence bracts, entire to rarely one-toothed floral bracts and sepals, shorter sepals and ovaries, and carpels with two ovules each.  Loeselia spectabilis is restricted to tropical deciduous forest in the Infiernillo region.  It is distinguished from the closely related L. grandiflora by possessing petiolate leaves, shorter sepals, glandular-ciliate corolla margins, and carpels with a single ovule.

The genus Ipomopsis (Polemoniaceae) encompasses about 29 species and 24 subspecies generally divided into three sections: sect. Ipomopsis, sect. Microgilia, and sect. Phloganthea. Leigh Johnson, Dieter Wilken, and I employed maximum likelihood and Bayesian inference of DNA sequences from the nuclear ribosomal ITS region (ITS1, 5.8S ribosomal subunit, ITS2) and the chloroplast trnL–F region (trnL intron + trnL–trnF intergenic spacer) to estimate phylogenetic relationships within this genus and its placement among other genera of Polemoniaceae. Results from this research are being published in Systematic Botany vol. 34. One of the major outcomes of this study is that we find support for the monophyly of Ipomopsis, but only if four species previously included in the genus are removed: Ipomopsis havardii, I. sonorae, Microgilia minutiflora ( = I. minutiflora), and Loeseliastrum depressum ( = I. depressa). Of the three sections previously recognized, two are conditionally supported as monophyletic. Section Microgilia (with 11 species and 11 infra-specific taxa) is supported as monophyletic if I. polycladon, I. sonorae, I. depressa, and I. minutiflora (the type of the section) are removed. This clade will be treated as section Elaphocera. Section Ipomopsis is inferred to be monophyletic with the inclusion of several members of sect. Phloganthea (I. multiflora, I. pinnata, and I. polyantha). The Giliopsis group (I. effusa, I. guttata, and I. tenuifolia) is supported as monophyletic by both data sets, and the cp sequences place it as sister to the remainder of Ipomopsis. This clade will be treated as the new section, Giliopsis. By contrast, there is no support for monophyly or paraphyly of sect. Phloganthea. Using the Eocene fossil Gilisenium hueberii to calibrate the most recent common ancestor of tribe Gilieae, we estimate that Ipomopsis has its origin 28.2 ± 0. 40 to 39.0 ± 1.14 MYA (trnL–F and ITS, respectively). Using this same relaxed clock, the node (or coalescent event) that defines the I. aggregata complex is dated at 16.2 ± 0.38 and 27.1 ± 0.83 MYA (trnL–F and ITS, respectively).



Loeselia tancitaroensis

Loeselia spectabilis

Ipomopsis: Floral form and variation in Ipomopsis: Section Giliopsis, (Section Phloganthea sensu V. Grant, in part; A–C)—A. Ipomopsis effusa (A. Gray) Moran, B. I. tenuifolia (A. Gray) V.E. Grant, C. I. guttata (A. Gray) Moran; D. Ipomopsis havardii (A. Gray) V.E. Grant (Section Phloganthea sensu V. Grant); Section Ipomopsis (E–H)—E. I. aggregata (Pursh.) V.E. Grant subsp. aggregata, F. I. tenuituba (Rydb.) V.E. Grant subsp. tenuituba, G. I. thurberi (Torr. ex A. Gray) V.E. Grant, H. Gilia polyantha Rydb. var. whitingii Kearney & Peebles (Section Phloganthea sensu V. Grant); section Elaphocera (sect. Microgilia sensu V. Grant)—I. I. congesta (Hook.) V.E. Grant subsp. palmifrons (Brand) A.G. Day, J. I. congesta (Hook.) V.E. Grant subsp. nevadensis (Tidestr.) Kartez & Gandhi, K. I. gunnisonii (Torr. & A. Gray) V.E. Grant, L. I. roseata (Rydb.) V.E. Grant. Scale bars for A–H= 5.0 mm, I–L= 2.0 mm.

DNA sequences

monophyly: Phylogenetic relationships of Ipomopsis, in the context of members of Polemoniaceae Tribe Loeselieae (Porter and Johnson 2000), inferred from maximum likelihood analysis (ML). The single ML (-lnL= 17862.76502) tree, based on comparative DNA sequences of combined chloroplast trnL intron and trnL-F intergenic spacer regions and nuclear ribosomal internal transcribed spacer regions (ITS1, 5.8S, ITS2). Bayesian posterior probabilities are adjacent to the corresponding branches. The small boxes adjacent to species names reflect the placement of species in Grant’s (1956, 1959) sectional classification of Ipomopsis: red= Section Ipomopsis, blue= Section Phloganthea, green= Section Microgilia. Clades corresponding to classification based on monophyly are indicated by colored boxes: yellow= Ipomopsis (genus), pink= Section Ipomopsis, green= Section Elaphocera, blue= Section Giliopsis.

calibrate: Chronogram of Polemoniaceae, based upon maximum likelihood (ML) analysis of combined chloroplast trnL intron and trnL-F intergenic spacer regions and nuclear ribosomal internal transcribed spacer regions (ITS1, 5.8S, ITS2). ML branch lengths were rescaled using nonparametric rate smoothing (Sanderson 1997). The tree was calibrated at the node indicated with an asterisk, using the fossil Gilisenium hueberii. Clades A–E indicate the target clades for dating using a sample from the posterior distributions of trees from trnL-F region, ITS region and combined data Bayesian analyses. Epochs of the geological time scale are indicated; however, the Pleistocene (yellow) and Holocene (white) are not labeled.


Darwin's Sexy Orchids: First Case Study "On the Origin of Species by Means of Natural Selection"

Darwin's Sexy Orchids

 O. mascula with enlarged diagram of its floral morphology. Gertrude in Hamlet called this flower “long purple.”

After the publication of Origin of Species in 1859, Darwin cast about for what his follow-up publishing project would be, and finally settled on the sex life of orchids, and how these plants uses various pollinators to cross-pollinate and eventually evolve new species through adaptation.

In the summer of 1860 while on a family excursion to what they called “Orchis Bank,” he observed insects pollinating the native British orchids.

 He sent several appeals through the Gardeners’ Chronicle to other interested persons to send him more information and specimens, which they did, and thus the book project was begun.

Charles Darwin

Charles Darwin

 These portraits were created shortly after Charles Darwin's marriage in 1839 to Emma Darwin.

Emma Darwin

 Emma Darwin

1861 was mostly devoted to this new book, which was finally published in May 1862 as On the various contrivances by which British and foreign orchids are fertilised by insects.

He noted to jmleph Dalton Hooker (Director of the Royal Botanical Gardens, Kew) that:

    I am intensely interested on subject, just as at a game of chess.

In September, he dissected with the greatest interest,” and noted that “the contrivances for insect fertilization in Orchids are multiform & truly wonderful & beautiful."


Darwin wrote to Asa Gray (Professor of Botany at Harvard) prior to publication:

    It really seems to me incredibly monstrous to look at an orchid as created as we now see it. Every part reveals modification on modification.

Publication was delayed because of illness, with Darwin calling the project

    a hobby-horse, which has given me great pleasure to ride.

In describing the pollination of British orchids, Darwin wrote,

    A poet might imagine, that whilst the pollinia are borne from flower to flower through the air, adhering to a moth's body, they voluntarily and eagerly place themselves, in each case, in that exact position in which alone they can hope to gain their wish and perpetuate their race.

2.	A first edition of Darwin’s work on orchid pollinatioin

<= A first edition of Darwin’s work on orchid pollination with a foldout illustration showing the floral morphology of Orchis mascula (L.) 1755, a native of Europe, including Great Britain.


Orchis Mascula Pollinium


 O. Mascula pollinium at the begining and end of the flight of the pollinating insect


 Darwin's Sexy Orchids: Specimens from Around the World

Darwin's Sexy Orchids: Specimens From Around The World

Catasetum macrocarpum (as C. claveringii)

Catasetum macrocarpum (as C. claveringii) in [Edwards’s] Botanical Register, vol. 10 pl. 840 (London:James Ridgway, 1824). Set purchased in London in 1928 by Garden founder Susanna Bixby Bryant.

After completion of his research about British orchids, Darwin went on to examine specimens from other parts of the world, many of which species had been sent to Europe during the great 19th century plant collecting “craze.”

A number of prominent British orchid growers (including Hooker at Kew) sent him specimens to examine, although of course the pollinators in most cases were unknown

He was particularly fascinated with the genus Catasetum, calling it “the most remarkable of all Orchids", and showed how in these flowers "as throughout nature, pre-existing structures and capacities [had been] utilised for new purposes".

Catasetum tridendatum showed its “truly marvelous” mechanism, by which it shot out a pollinium at any insect touching a part of the flower with “sticky gland always foremost.”

Darwin imitated the action of an insect touching the flower’s “antenna” using a whalebone spring.

    I touched the antennæ of C. callosum whilst holding the flower at about a yard's distance from the window, and the pollinium hit the pane of glass, and adhered to the smooth vertical surface by its adhesive disc.

Catasetum macrocarpun (as C. tridentatum)

C. macrocarpum (as C. tridentatum) in Curtis's Botanical Magazine, vol. 61 pl. 3329 (1834).
C. marcocarpum (as Monachanthus viridis)

C. macrocarpum (as Monachanthus viridis) in Edwards's Botanical Register, vol. 21 pl. 1752 (1836).

He conducted experiments to determine just what caused a pollinium to be released, including:

  • Fall onto a table from a height of 2-3 in.
  • Cut off with a crash with scissors
  • Deep pricks of the column and stigmatic chamber
  • A blow hard enough to knock off the anther (an accident)
  • Press hard on pedicel and rostellum
  • Nothing works except “violence” to the antennae (not including stream of air, cold water or human hair)

He also solved the “problem” of Catasetum macrocarpum [=tridentatum], flowers of which had been described not only as three separate taxa, but in three genera.  Lindley had stated, “Such cases shake to the foundation all our ideas of the stability of genera and species.

These Darwin determined were just male, female, and perfect flowers on the same plant sometimes at different times.

Catasetum macrocarpum Rich. ex Kunth (1822)


  • Monachanthus viridis Lindl. (1832) =Catasetum trifidum Hook. (1833)
  • Monachanthus viridis Schomb. (1831) =Catasetum barbatum Lindl. (1844)
  • Monachanthus viridis Lindl. (1836 publ. 1835) =C. macrocarpum FEMALE
  • C. tridentatum Hook. (1823) =C. Macrocarpum MALE
  • C. tridentatum, var. viridiflorum (1834) FEMALE?
  • Myanthus barbatus Lindl. (1836 publ. 1835) =C. barbatum BISEXUAL?
Darwin's Linnean Article

Darwin, Charles.  “On the three remarkable sexual forms of Catasetum tridentatum, an orchid in the possession of the Linnean Society.” [Read 3 April] Proceedings of the Linnean Society of London. Botany 6: 151-157. 1862.  Darwin read this paper, an extract from the book, the month before the book was published.


Darwin's Sexy Orchids: A Life Full of Orchids